using early ramhorns on a 350

[63burban4x4]

I'm preparing to install a circa '86 350 from a C-60 truck (low,low miles)
in my '63. I'm looking for good driving dependability, not a high performance motor. I putt around town, but do plan some long distance travel with a camping trailer. Not changing cam or valve train, but will probably change the governed 2 barrell carb to a quadrajet. Panning for a 2004R trans, and am running 3:73 gears with close to stock height tires.
My question is this, I guess the original 283 ramhorn exhaust manifolds probably have smaller ports than the set of ramhorns that came with the 350. Thing is, all the original '63 pulleys and brackets for the front of the motor work beautifully, except the newer ramhorns have no mount for the alternator, like the 283 ones. If I use the 283 manifolds, I'm done fooling around with pulleys and brackets. If I use the 350 manifolds, I have to fabricate a new mount somehow for the alternator.
Question is, will this have a noticeable performance difference, if in fact the ports are smaller on the 283 manifolds?