What carb came on it? I also think converter is bad and responsible for the missing mph. Is this the aluminum head version? My 408 dressed model came from them with a 825 mighty demon. That is 825 cfm wet flow, not like most other cfm ratings. So in the future it might like a bit more carb. Mine ran 12.47 at 110 back then with the stock eddy heads. If you break that rear remember to have the sprag checked in the trans.
