How do I know what V8 I have?

[ClassicCar.com]

I live in Perth Western Australia and have just bought a 1979 Chevy Caprice classic. It has a V8 but how do I know if it is a 350 or a 305. From the VIN number, I have concluded that it is not the 305 (code U), but how do I tell if it has had a replant or not. Any tips would be great. Cheers

[ClassicCar.com]

get the casting #'s off the block. THey should be located on at the top rear of the casting were the bell housing would attach. Then compare those #'s with the list on this site.
http://www.mortec.com/castnum.htm

[ClassicCar.com]

Cheers for that