AFR 195 heads will support 500 horsepower in a 383 @ 5,500 rpm's. (610 cfm @ 100 % efficiency). A 327 turning 6,440 rpm's passes 610 cfm @ 100 % efficiency. Is there any reason not to think the 327 would make the same power?

You do raise a good point about the block. I forgot about the main caps. It seems like I've read that they're good to about 400 horsepower or maybe a little better, so a change to Milodon 4-bolt caps in the three center positions would be real good insurance.

Hey, who knows, I might be full of hooey. Some of you other guys should jump in here and play the devil's advocate for me.....