afaik you need a 4x4 block if your gonna go silly power
all internals from your 2wd will fit the 200 block, but if you change to 4x4 pistons then you won't get any piston slap atall.
I would think 350ish bhp would be ok on a std 2wd bottom end.

my car is approx 350bhp using 4x4 bottom end and 2wd head