Patrick,
I assume that you have seen the
Racer Brown-Frank McGurk article in the May 1955 HRM? Note that the addition of a Corvette six exhaust manifold and dual stock truck mufflers increased the torque (and HP) by four to better than five percent from 2000 rpm and up. I've been told that Fentons flow better than the Corvette six manifold,but I was happy with the Corvette six manifold that I had on my 261 back in 1958.
As Tom says, these engines need help in breathing. Note that even with three carbs and a pretty good cam the speed for peak torque was still only 2000 rpm.
