jerry-
There were (and likely still are) 'forward swept intakes' being mass produced that really lengthened the intake runners.. This can really add torque to a motor. I'm sure you may agree the trick would be matching the exhaust to work in unison..(like U mentioned in your post)..
Friend of mine made a dual runner intake for his HD Flathead & runs 2 carbs as well.. Really helped his scoot get up-n-go..
But what do I know ?? My fav personal bike is still my Flathead also.......
