Horse power drop using early A 273 manifolds

I was just thinking, that leads to drinking but that a whole another post.

I cannot find anything but has anyone dyno a 318 in a car with original 318 manifolds and then dropped that 318 in an early A (or just swapped the manifold out) with the power steering clearing manifolds and redyno to see if loss or gain using those manifolds over the stock 318. I know a lot of people swap out a 273 for a 318 and wondered how much (if any) it hindered the engine? Not much beats headers. But if you stick to factory, I just wonder how much it hurts.
thanks. Syleng1