Small Block & Big Block Chevy Specific - average hp for a crate zzr 383 motor

I know nothing about older 383 crate motors but I need to know about average run of the mill hp for these things. I have a friend who has one that he already blew the pistons to hell because he can't get it tuned. He has rebuilt it and has a big ass holly carb on it. He thinks he is going to but bus lengths on the all might ls1. It has big heads and cam but don't run very good because of his lack of tuning knowledge. Every time it starts, it dies or will idle very high. He just starts adjusting the carb everytime he starts it until it idles. Then it will jump idle and die again. This is in a heavy 1991 trans am that still has the stock rearend. The funny part is, it don't even have a posi track rearend and sits on the stock 14 inch tires. He just put his tranny in and he keeps telling me he is going to bust my ass. If it were properly tuned and he had ANY traction, he might have a chance but I doubt it. Do I have him covered already with my mods on motor. It put down 380/385 on motor before I added true duals, ported t/b, 25% u/d pulley and 4.10 gears. It should be around 400/400 now on motor. Do I even need the hose to wax that ass like raindance? :devil:

You'll EAT him...You'd probably eat him if U were stock, from the way it sounds. I figure he's probably got the FastBurn's for heads. Not any better than a stock LS1 head, probably got the ZZ4 or the HOT cam....Your stock LS1 with bolt-on's probably made more RWHP than his is going too..