Can I use B or C body manifolds fore better flow on my sleeper GTS?

If you use the B-body manifold, would you share the modifications needed to fit your application. TIA

Driver side manifold was on the shop doorstep this afternoon! A sincere thanks goes out to Jim/fishmens67 for donating a very nice specimen. I will take some comparison pics when I get back out for "2nd shift" aftrr everybody goes to sleep. What can I say, vintage cast iron gets me excited.