[Too Many Projects]

Not sure why you don't want to just tie the headers into the Gardner, unless the 2.25 will be considered too small.

I have Pypes 2.5 header back on my '67 with the Race Pro mufflers. My 350 is mild, about 350 hp. It's quite mellow with reasonably normal driving but will make her presence known when she is in the loud pedal. The mufflers tuck up under the rear seat pan about as good as any muffler is going to where none were ever intended to be.