Griff, LT1 heads have no conventional water passages in them through the intake manifild, They use a crossover tube in the back of the block to transfer water head to head.

 

So you cant use them on the old style block? What factory gm heads(cheap) would you recommend, I see all kinds on ebay. Are hardened exhaust seats necessary if they are is 1974 the year they started to be used. Thanks