I don't think you should use the Ork Horde detachment. It's pretty sub par. Especially on an army that uses such massive, durable troop units. Here's a thread on why, but don't necro it unless theres something important that has yet to be said:
http://www.dakkadakka.com/dakkaforum/posts/list/0/614150.page#7183930
That aside, I do have some nitpicks with the list.
Nitpick One: The Meganobz. Meganobz are great and fun and cool, but that is the only vehicle in the list, and its av10 open topped. It will be blown up turn one and your entire
Manz missile and warboss will be rendered entirely useless for the whole game. Even if you hide out of
LoS turn one, a crafty opponent will find a means to destroy it. In my opinion, if a list is going to take trucks, it needs a minimum of 3.
Nitpick Two:
Kff mek. New
KFF isn't that great. It's good for protecting a VIP vehicle like a battlewagon or stompa, or for keeping a small elite unit another layer of safety. It's not good at blanketing hordes anymore. I'd leave him at home.
Nitpick Three: Lootas are also out of place I think. You'd be better off with a battery of Lobbas or megakannons or something. Because of your big blobs of boyz, they'll be able to swamp in melee pretty much anything that your lootas would be tasked with killing.
Nitpick Four: Warboss can't have two relics at once.
In my opinion, if you wanna run a dedicated footslog list, drop the Mek, and ditch the Warboss' mega armour, and cybork, because he should be in the same mob as the Painboy. Pull the Meganobz out of the list as well- they're too easily shut down. Replace the Lootas with Lobbas or MegaKannons, and use the points you saved from ditching the Big Mek to buy a min sized unit or two of grots to run in front of your horde to get you a cover save and to take charges / tank overwatch.