i have a UT t38 but it's on a well overspecced engine to be honest.....making 450ish bhp now,so it's pretty much on it's limit.a T34.63 will do 400bhp,so don't discount it totally.

if i were you i'd go for a ported head (Karl does a low lag stg 1 head that is very very good,i had one on my last cossie)

i'd get the standard pistons pocketed as you'll be changing cams (although these probably won't be wild cams,but it's a good mod to do in case you go for lairy high lift cams in future)

greys will be fine,L8 would be a good option to get a good smooth economic drive