I like the list but see you running into a problem agenst armour,,,, aa battle wagon with a deffrolla would really mess you up,,,
id probly go with switching out you warboss with a big mek with burna and a
kff. Since you only have two squads of 12 boys there not going to last one round of shooting, so the
kff could help you out abit there to.
Also maybe put in afew mekboyz with kustom blastas to help take out tanks. Cause untill the enemy is in range of the burnas there pretty much moving targest.(the
kff will help keep them alive). Also (i know this sounds like changeing your whole list) but the bikers wont do you justice. I run a biker ork list and a squad of 3 bikers will eather got shot to bits or run quicker than a grechin thats on fire.
Id say replace them with scorcha trakks or more killkans. All the best on the list hope i helped