Normally, someone posting a useless "Sigh" in regards to me noting a lack of competitiveness would bother me, but since I did couch it inside of "Not saying it can't be done..." I'm going to let it slide. I provided some helpful advice towards the Fully Armoured idea immediately afterwards, so I can say I was helpful.
Mechanized infantry in 8th edition is highly ineffective. The points spent on infantry, and their upgrades, can't be taken advantage of while embarked. No firepoints. And moving with a Chimera or Taurox diminishes their firepower, and moving forwards does that AND exposes them to greater risk. They're really better off sitting still in your DZ and being fire support, instead of a transport, and they're inefficient at that task.
Whereas infantry moving forwards on foot can still utilize their weaponry. I'm not up on the
CA points adjustments, but going out of the codex...
Infantry Squad w/ Bolter, Plasmagun, Heavy Bolter, 7x Lasguns = 62 points
Chimera w/ 2x
HB = 91 points.
For one Chimera + one Infantry Squad, you pay 153 points, and if the Chimera moves you get to fire 2x
HB at -1 to hit and 6 lasguns. Two of those is 306 points, and can fire 4x
HB at -1 to hit and 12 lasguns.
5x Infantry Squads cost 310 points. You can fire 5x
HB at -1 to hit, 5x Plasmaguns, 5x Bolters, and 35 Lasguns. Said units can also benefit from orders... and if you're cheeky you make a conga line so your
HB's don't have to move and thus suffer the penalties for moving... so they fire at full
BS.
8th Edition rewards killing them before they kill you. That means maximizing firepower. You can't do that when 40% of your points can't do anything while embarked, and the remaining 60% of your points suffers for moving forwards. I mean, what's the point of a transport that is worse for carrying infantry AND worse for moving forwards? It's just going to result in loss after loss. You just can't output enough firepower to make it worthwhile.
Whereas infantry moving up with "Battle Tanks" increase the value of the tanks by protecting them, and the infantry can still fire. Further, with careful placement, you can protect units behind battle tanks (out of *some*
los) from most return fire, while keeping your own firepower active. That's the win-win of combined arms for
IG.
I have Chimerae and tried them out when 8th rolled over and was consistently disappointed by the results. They're too expensive and actually hamper the ability to win by using them as transports. And they aren't efficient at being fire support. A Basilisk is 100 points, and the Chimera is 91 with a pair of
HB. You upgrade one
HB to an indirect firing Earthshaker for 9 points. There's no contest.
Which is why I'd honestly suggest adding Knights if you don't want to use foot sloggers. Keeps the Mechanized force, without requiring Chimerae. Even then, foot sloggers are vital to the attrition style strategy that
IG plays so well. They're part of the tools in the box that
IG has to use. If you were doing a job, and you decided not to use a particular tool, like a screwdriver, you can pound a screw into a board with a hammer. I doesn't work as well, but if you want to you still can. But know that you're choosing to make your job more difficult by not using the screwdriver, and that may become frustrating after a few jobs (games.

)
_____________________________________________________________________
But what you asked for was list advice, so here's what I'd suggest. Again, probably better off starting at 1000 points and building up. Nothing is so defeating to your hobby morale as a hundred primered infantry and a half-dozen tanks!
Brigade:
2x
LR Tank Commanders (More points efficient then
HS Leman Russ)
1x Company Commander (For Orders)
4x Infantry Squads
1x Commissar (Elite Version)
2x Armoured Sentinels
1x Hellhound
801 points - No Upgrades - 3 tanks and 2x Walkers. You could probably trade the Sentinels for another Hellhound if you were inclined.
I personally like having sponsons on the Russes, so I'd go for those. I like having a heavy and special weapon on my Guardsmen squads, even if I plan on moving. For a turn or two, you can not move the Heavy to fire at full
BS if you leave a line backwards to it, and even if you move, I find they're still worth taking. Armoured Sentinels are pretty tough if you can keep them in cover, and can act as a speed bump and sniper rifle if need be (I like Lascannons... poor
BS be damned!) and the Hellhound can be flavour of choice, but I like the standard Hellhound with Heavy Flamer. Move, shoot, no worries.
If you have points left over after your upgrades, another Infantry squad just to leave behind in your Deployment zone, out of
LOS, holding an objective could win you the game. Just stay alive, camp an objective, score
VP at the end of the game. Good times.