Dont have all the specs but i bought this motor used about 6 years ago. It was rebuilt and runs great,but just feels underpowered.

I have had it in my roadrunner for about 3 years.
Its a 383, SRP pistons?, mopar hydraulic purple shaft unknown lift/duration, 906 heads,eddy perf intake,Bigs 780 vac carb, headers. msd ignition,timing at 38 total.

Its an auto,2800 converter,4.11 gear.
Car runs great, besides it feeling underpowered.
it doesnt have the pull that puts you back in the seat. I just got done building a smog 440 with the a summit cam it it will destory this mild 383. Is this just the nature of a mild 383 with (im guessing) low compression?

Anything you guys reccomend doing/checking?
thanks!