[AZKen]

I think this is in the wrong forum:

If "electronic distributor" means HEI, like a modified Buick dizzy, that's for reliability. A spark is a spark. As far as the holley, it's been dyno'ed and shown to have no effect. The science says the motor, as designed, can not use more than 300-350 CFM. It's volumetric potential is 300 CFM. The engineers who designed this fabulous motor studied every system and used carbs for maximum volumetric efficiency and overall motor performance. Which was the main goal as well as long life. If you are after more something, what is that something? An unknown motor should not be tested to max. Which is 3800 to begin with. Why are you testing at 3950-4000?

If you want more of certain things, get a SBC or BBC motor that will go 6000+ and save cutting up/modifying a 305.

The motor was built for reliability and torque. Built for highway speeds of the era. Built for heavy hauling. It is way too heavy. There are no speed parts made for it. It's limited but strong. It's not a "performance" motor.
The science/physics is real. You can not naturally aspirate more air thru this motor by just putting a bigger hole on top.

A chassis dyno measures drivetrain output not motor output. Changing differential ratio, tire size, trans and adding OD will improve drivability and some numbers on that test. Due to the many tolerances, variables and losses/resistance in the drivetrain/transmission, you can only extrapolate values assigned to the motor. This method is not used to compare motor part changes.

I applaud your ambition. Sounds like it's running good, enjoy it.