If anything, I would want to advance the timing right? I suppose I have to be the tester on this one.
It wouldn't take much to change the timing and see how it works. I have been told that advancing the timing one tooth will give a boost in power AND mileage. This came from a guy who has been messing with timing for 25 years. Race cams are retarded to give more high end to the motor. I want torque, so I would advance the cam to bring whatever top end it has, down.
I think I need new valve springs, because they sound like they are floating above 3500. It sounds all garbly and rough. The motor on my sawmill did that too, until I stretched out the springs.....