Just how ridiculous would this be?

DionR said
I run Magnum R/T heads and a stock alternator setup and don't have any issue with the alternator not fitting.

There is something else going on here. Maybe you are using the wrong groove in the crank and water pump pulleys? If you started with an AC setup, seems like the belt routing and brackets are pretty different. Like maybe the water pump pulley is wrong for a non-AC setup?

Not really sure, but I know it works without having to re-engineer the entire setup.

I see lots of pictures with aftermarket magnum heads like tgese with a flat surface. The problem im have is this part of the casting that sticks out is hitting the back of the alternator case