wisco 10:1 piston (IF YOU GO 11;1 YOU MUST USE RACE GAS WITH NO EXCEPTION). bored .80 over (416) your hot cam stage 2 would be fine. i would prefer a stage 1, it has a better mid range. the stage 2 has a better top. the cdi box i would go with a tc box
Never build one with a 440 kit(Not reliable)....the best(most reliable) 400EX engine ever built was a 416.
-One other thing i would do is cut the flywheel, this is a must on any high performance 400EX. tc can do this also. it runs around $100 + shipping.
-Edelbrock is a good carb.
but it is very expensive. For reliability that is what i would go with... THE high maintenance carb. but the best carb. is a lectron, get one thru tc noted. Remember this carb. IS high maintenance and difficult to install proper. The other option i have not tested myself is the stock carb. off the 04' - 05' 450r honda, you will have to do your home work if you go this option....
-contact him at 814-723-3514