You should probably move this to the 351c board. Anyway three holes on the cylnder banks on the block, just use the new gasket as template. The heads need to have one hole plugged and another hole opened to allow water transfer. The valve reliefs in the pistons are different. The final piece is a special intake manifold from bush performance($450) or intake adaptor($250). The cost to build a clevor is not really that bad. But I caution you those heads flow 275 cfm stock. They like rpm or cubic inches. Truthfully they want both especially with porting. How extensive is the porting? Are they hogged out? With a good set of clevelands no one doubts 10's are there. What are your goals? I'm using them on a 427 clevor. In theory they should pull hard to 6500 and 450+ should'nt be a problem