the fan shroud is metal and their was a small block in the car. i plan on putting a big block in, what is the different in the shrouds? will this shroud work or will i need to replace it with the plastic one?

Replace the metal one with the plastic. The metal is for small block.

The metal shroud is too long and won't fit in front of the BB.

Main thing is the metal shroud, which is circular and 20" in diameter will restrict flow of air though the radiator when not moving and the fan will sit too deep in the shround and not pull air though. Get a BB radiator, prefer 4 row, BB shroud, and the right size spacer so the fan blades doesn't set two deep in the shroud.

Souldn't have a shroud unless it's an AC car.

I don't think 'correct' is the issue. Do yourself a favor - use the BBC shroud and radiator. I hate watching the temp gauge in traffic, worrying about it.
John

Ed, Don't forget about A.I.R. cars....which also got the shroud. ;)

thanks guys, i will order a new one.

I stand corrected Mark.

Also HD RAD got the shroud in addition to the AC or A.I.R. Cars or dealer added.