Will 1995 L99 Chevy heads bolt on a old 1983 350 block thay look the same on the out side. i can get a set for free and figure thay would have a 56cc chamber i want to run them on my demo engine hlp?

Yes, they will bolt on, but no, they will not work. They are intended for a reverse flow cooling system, and also the intake bolt pattern is different from the pre-86 small blocks.