Nothing wrong with the EFI heads, but you will need to modify a good aftermarket dual plane to fit, if you don't want EFI and headers may be a little bit of a problem finding something to fit your chassis with the raised exhaust ports.

I woud do a Early 460 with some decent Factory Iron Heads (DOVEs or the like) Good Dual Plane, 850 Carb, Nice FT Cam + a few other upgrades. You can get 450+hp pretty easy and still be very drivable, very torquey and Inexpensive.

C6 would be the easiest, but you could adapt a GM 700R4 of 200R4 to it?

As far as blocks go they are all a good foundation, their are no bad ones for builds in the 600hp range

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2008 New Years Resolution "Break into the 15's with a JA Custom Cam"