SP2P 2bbl worth the effort?

So for the beast, other than timing chain and oil pump, it's untouched. Has the factory Holley 2bbl. I have a K&N air filter in the stock housing with fresh air tube hooked up to housing. Manifolds with 2-1/4" pipe run into hooked turbo mufflers and a H pipe before the mufflers. Ignition is factory electronic converted to HEI, heavy and a med-light springs. 8* initial, 36* mechanical and 54* with vacuum.
Truck runs 3.21 gears and 31x10.50x15 tires. The old girl purrs at 62mph and actually gets better milage than my 97 Ram. Always try to improve on it, but i think I'm just about as best I'm going to get with the current set-up.
Thanks