383 rebuild - kinda whimpy on the dyno?

What were the clearances on your bearings. If tight and the oil was not up to temp, that will scuff and kill them quick.

See more details of my project where I have more details of the build.

All of my mains were between .0015 and .002”.

Connecting rods were: .0015”, .0016”, .0016”, .0016”

Crank endplay: .005”