Most people don't play Ghazzy anymore as he's a lord of war and, even if you are playing Lord of Wars, the stompa is better.
Run him as a Warboss in Mega Armor + the Lucky Stikk, he gets a 2+ re-rollable save (more info in the codex).
Put him in a Battlewagon + Ram + Boarding Planks + 2 Rokkits
Give him a MiniMek to accept Challenges from anything which has AP1 or AP2 and can hit you first. Orks no longer have Invulnernable saves in
CC 
That means the Battlewagon has 17 spots left. Put Slugga boys in there with a Nob +
PK +
BP.
Deff Dreads are somewhat useless to orks these days. I havn't seen many lists outside of truely dedicated walking dreads use them. Unfortunately orks have 3 Heavy Support Slots, and, compared to the other things you can get, the Deff Dread isn't good.
With 15 Nobs, and a Warboss, the best thing for you is to look into the Ork Suppliment book - WAAAAGH! Gazzkul. There's a formation in there which allows you take 10 units of boys and a Warboss with them. It's one of the more successful and fun ways the army plays, however at 100 units it IS a horde army. Are you in the mood to move 100 models?
The list normally goes something like this:
1st
CAD:
Painboy + Finkin Kap (If this guy is your warlord, then you'll be able to re-roll on the infultrate option, IF your lucky you'll get it and 100 boys infultrating is frightening)
Weird Boy level 2
2x 10 Grots and a Runterand.
2 Mini Meks + 2 Buzzsaws.
Formation:
Warboss + Eavy Armor +
PK +
BP (if this guy is your warlord, then you get to Waaaaaaagh! every turn after turn 1, which'll mean you get to close the gap a lot faster)
7x (9 Ork Slugga Boys + 1 Rokkit + 1 Nob +
PK)
3x (9 Ork Shoota Boys + 1 Rokkit + Eavy Armor + 1 Nob +
PK +
BP (the extra
BPs are only if you really think they're required, you'll probably only need 2/3 in the entire 100 boys)
The main idea is that you'll be joining the Painboy, Weirdboy and mini Meks to the 101 orks:
-- This list allows you to take 13
PKs. They'll most likely be able to get into combat for that. Orks boys are pretty easy to get ahold of.
-- The Painboy will give the entire 101 boys
FnP, which is definately one of the strongest tactics orks have
ATM.
-- The weirdboy can do some nasty stuff. Like teleporting the squad, or increasing the squad's strength.
-- The 30 boys in Eavy Armor are there to soak up any wounds caused by the Mob Rule, as you're allowed to allocate the wounds, rather than randomly (perk of the Formation).
-- The Grots are there to fill troops slots. You don't really need more boys.
-- As everything would be running on foot, you could potentially run the Deff Dread along side the unit, however I'm not sure how effective that is.
A of lists I've seen the above run have Lootas or Traktor Kannons at the back for air support, as you have none otherwise with this above list. If you get an
ADL, then the Grots can hide behind it and fire a Quad Gun and actually do some good damage.
Other things you might like to think about:
-- Tankbusters are awesome these days. Typically 5 in a Trukk + 3 Bomb Squigs or 15 in a Battlewagon with a Painboy and a MiniMek + Rokkit.
-- Meganobz: most people run at least 1 Missle of these guys: 3 Meganobz (1 with a
BP and sometimes 1 with a Skorcha) inside a Trukk + Boarding Plank + Ram. Aim it at something. Go Flat Out first turn. Never expect it to see turn two. If Meganobz don't make it to something to kill, they're gonna struggle to do much as they're Slow and Purposeful (like the Mega Armored Warboss) but (like the Warboss) if they get there, expect them to cause A LOT OF HURT.
-- Lootas have gone down in price online as they're not "the best" heavy support unit these days. It has to fight for a place against the Battlewagon and the Mek Guns. They are still awesome and have longer range than the Mek Guns.
-- Mek Guns: 3 types to look out for. Keep in mind that Ammo Runts give you a Semi-twin-linked option.
-- -- Lobbas: 18 pts each. Strength 5
AP 5 Barriage and REALLY nice range. You can hide this in the most hidden place possible. Do that. These things are great against hordes and are good at sniping sargents.
-- -- Kustom Mega Kannons: 30 pts each. Strength 8 AP2 Blast and the "Gets Hot!" rule. While this thing has shorter range and needs like of sight (unlike the Lobba) alot of people really like these things. It's ashame it has shorter range but for what it does, it's a Mork send. Most
-- -- Traktor Kannons: The best anti Flier, anti Flying Monstrous Creature weapon IN THE GAME. Same price and range as the
KMK and Skyfire now allows you to shoot at skimmers. The Traktor rule is the key tho. However, how many you want all depends on how your local meta plays. If your local gaming group doesn't have many fliers, then only 2-3 would do.
Most Ork Gun lines will run 2 CADs so they get 6 Heavy Support slots and fill them with Lootas, Lobbas,
KMKs and some Traktor Kannons (maybe with some Kannons too, points permitting). The key with a Gun line though is that
ADL. It gives the Lootas a much required 4+ cover save. But this type of list needs a combat piviot (which Mega Armored Warbosses or Meganobz are very useful for providing).
MAJOR NOTE: Trukks are a death trap for anything not in at least Eavy Armor. Trukks like to explode. When they explode they'll deal
D6 Strength 4 wounds to everything inside. Randomly (keep that in mind about your
BP holder). If you suffer more than 1/4 losses, then you'll also take a further
D6 strength 4 wounds from the Mob Rule (otherwise you'll just run away). Orks with only a 6+ armor save struggle to survive in Trukks. So unless there are other things which your opponent needs to take care of first (like a Meganob Missile), USE WITH CAUTION.
I hope this helps.
