[jagarra]

Ed, you have some good points there. I figured the change in RPM at 65mph would be 346 RPM lower with the higher gearing 2320 vs 2666 now. Best part it would raise the cruising speed by about 10 MPH.
Still bouncing the idea around. Most of my driving is in town or the surrounding area. I rarely go on the freeway for any distance. I keep going back to the 85% rule once told to me by an industrial engineer. You build for 85% of your activity. So the gearing I have falls into that usage.

Seems I would have to change the yoke too as most all the ring and pinions have the fine spline on the pinion. From what I have heard the original GMs had a coarse spline and the Chevys had a fine spline.