I e-mailed the owner and he said the following:
"The guy that owned the car before me lost the trim tag.
The motor number is a 68 396/375. I don't know the tranny number or the rear number. It's a Muncie M21 and a 12 bolt rear. I replaced the rear quarter panel with GM replacements remover the front clip sandblasted & painted the frame back to the firewall. I Rebult the
motor, tranny, and rear. I painted the car back to the original color Dusk Blue. The interior in blue metallic."
Seemed awfully open ended to me.
Blair