[82ACAUTOCRAFT]

I don't think HP loss in aluminum blocks is an issue, they use steel liners anyway. Aluminum heads however, make a tiny bit less power than iron ones because of greater heat dissipation but this is offset by a greater resistance to detonation still because of the heat dissipation. The only problems I can see with alloy blocks are those due to porosity, expansion and the softness of the metal and those of course can be solved with proper enginering and machining. Sand casting is not the best way to make strong parts in aluminum but I suspect it is the process used by Genesis, Pond and dove, is it?
One thing I have noticed after installing Edelbrock alloy heads and Intake M. on both my FEs' is how much cooler the engines ran! I have had no problem with either motor by the way. I just bought another original 427 block, this is the one I will use, it is drilled for hydraulic L and came off a Fairlane. It is going in an original car and after the car is painted, I want to forget about the motor and not worry about leaks or other mechanical issues.