Horse power drop using early A 273 manifolds

cudamark said
In '68 and '69, the 273 and 318 used the same exact manifolds, so, how can there be any difference? If your question is whether using the '64-6 LH manifold instead of a '67-up LH manifold, I doubt there would be much difference since the 273HP engine had 235 HP vs. 230 for the stock 318. Now, with engine mods, and/or high RPM, you'd need some dyno testing to see what differences there might be.

And that's exactly what the OP was pondering: if a 318 swapped into an early A ('64-'66) using the original, and appearingly more restrictive, 273 manifolds pictured in post #8, would see any measurable dropoff in power with 45 additional cubes trying to breathe through them; and if there was any known dyno evidence of this compared to later ('67 and up) manifolds.