So, I'm pretty sure the culprit is the starter clutch as suggested by Scottly and Godffrey. I swapped in another starter and same result. I worked through electrical potentials and was able to eliminate all of them. Wired the new starter directly to the battery and still heard the sound. When the plugs are out, no compression, sound isn't there. What I think is happening is as the clutch engages it slips like mad. I checked it when I pulled the starter and everything felt good but since it isn't engaged under loadI'm not going to be able to tell anything.
I've started pulling the needed part numbers to order. Could use some confirmation that I've got the right ones....
I think I need 8, 49, 50, 77, 89, and 90 for the rebuild, yes?
I also got my tail light mock up parts back from the printer. Need to make some modifications but I'm on the right path.