While it would obviously be more difficult than simply bolting on a spacer, and also obviously more expensive; significant power, economy, AND driveability could be acquired by changing your intake/carb to a genuine Chevrolet 350 spread-bore intake, and either an original Chevrolet Rochester Q-Jet designed and calibrated for the 350, or the Carter aftermarket Chevrolet TQ.
Other than time and expense, the downside of this upgrade would be losing "cool points" at the car shows to the 16-year-olds.
Jon.
