1991 360?

I agree the 596s are good heads. I havent seen too many, but I haven't seen any cracked ones.
But - If you're building basically from a blank sheeet of paper, I would definately ignore any open chamber head, and the RHS LA-X heads are close to the same money as a set of performance 596s without porting, and the RHSs will flow better than 596s in that form.