It seems like more cam and compression than a buddies 1969 340 4 spd car with stock cam, motor seems very healthy its just more of a desire to get into the RPM quicker, being an auto, and getting rid of the surge when cruising. i had begun to believe it was from lack of vac advance, the fuel smelling exhaust could be settled down also, just unsure if thats the cam or partly the timing. Dont notice fuel smell when driving, beyond being an older design motor.