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

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.
He's a good dude for sure. I'm likin what I'm seein! Lots of cool old school stuff. This things gonna haul the mail!