Hey guys, glad to hear that bigger isn't always better.
mts, my cousin had a '69 bird, back in the '70s. It was quite a desireable car to have in our neck of the woods, and I have to admit, I'd love to have one like it today.
Siggy, you said what I was thinking. Bigger diameter could affect the backpressure and sacrifice a bit in the performace dept.
Keeping in mind that mts' son will be the primary driver, maybe that wouldn't be a bad thing....