Junkyard 6.0L build?

[clay69camaro]

I've looked online for prices of an iron block GM 6.0L and some of the adds specify the 8th digit on the block being a "Z" or "T". What's that all about?

I simply want a 6.0L that I can build for a twin turbo set-up. What should I be looking for at a junkyard or online? What kind of head options and intakes will bolt onto this block?

Plan is forged rods/pistons, ported aluminum heads, and get rid of the truck intake. Haven't dove into turbo options yet but something like two precision 76mm turbos or a trick borg warner set-up.

Thanks

Clay