2.5 to 3.0 Exhaust

I have large exhausts on my cars, (3 and 3 1/2), but for your low compression 360, 2 1/2 is just about perfect. Going to a three in your case will gain nothing but loud, and maybe hurt.
Engine masters have done 2.5 vs 3 on both a stout big block, and a mild 350/383 .
Big benefit on a 600 hp big block, nothing but louder on the small block.