I think it depends on the power level your after, 350 hp and lower small would be easy choice, 350-450 hp you could go either way 450 hp plus I be definitely thinking big block especially in a street car.
yes, but don`t use a 440 block w/ raised port heads. it`ll be just as bad as putting a hemi in one, w/ exception of pass. side fenderwell clearance---ask me how I know!