friends have small blocks. all i hear from them is i'll show you a fast small block. and they are fast no doubt.
it depends to me what you want in the end. i my self think a 500" big block can be built with normal parts new or used till you bust the block.
the fast small blocks tend to be more non normal stuff. big heads have one off valve trane and headers.at higher rpms.
but those 4" crank motors make great power. and leave hard.

it is up to you what ever you want i my self think a big block stroked will make power cheaper. but i may be wrong and it depends how much power you want.