Ok, firstly the Warboss, I agree on cybork body. Everything else Boss wise is fine, but if you've got points combi skorchas are nice and you don't need to work about the crappy ballistic skill.
Big Mek is fine, only thing I would add definately is a boss pole in case those Lootas run once the wagon gets popped. A power klaw could come in handy in case they get assaulted, but I don't think its a must.
15 Boyz on foot is small. I would up it to 20. Also if I remember correctly its 2 special weapons per 10, so you cannot have 2 big shootas unless you take 20 Boyz.
Trukk Boyz are all fine. I wouldn't be inclined to use reinforced ram, the Trukks will get taken out easily and you don't want to invest too much points into them. Boarding planks come in handy with those power klaws and keep your units wrapped up in metal still, good choice
I would add another Deff Dread, drop the Looted Wagon as they cannot always be controlled due to that silly special rule.
Kans are ok, not sure on rokkits as they haven't got the best ballistic skill. I'm sure a big shoota for anti infantry would be better, or perhaps a grotzoka. Something to consider, the Kans are in a squadron and armour 11, squadrons make vehicles weaker.
I'm not keen on Storm Boyz. I don't think moving 12" with 6+ armour save is very good. And if they deep strike they are sitting in the open ready to be shot. Some bikers would be better, but I get the impression your taking them for the special character?
I would be inclined to take 2 loota units in 2 battlewagons.
If the battlewagon is a fire bunker for the lootas I don't see much point in a red paint job because if it moves then the lootas cannot shoot, if it moves more than 6" the kannon cannot shoot. You haven't got the need to get the lootas anywhere fast, so I don't think its needed.