273 Commando Rebuild Or Not?

Hello All,

I picked up 67 273 Commando. Did a compression test on it today.
Here were the results from the cylinders:
1) 155 psi
2) 150 "''
3) 155 ''''
4) 140 ''
5) 150 ""
6) 140 ""
7) 155 ""
8) 140 ""

Shot oil in the low cylinders and the compression rose indicating ring sealing issues.
The engine supposedly sat for a long time. Back three cylinders are obviously low. The manual says 130-165 psi and + or - 25 psi between cylinders.

The engine is in the back of my truck so I can't hear it run. The prior owner mentioned seeing white smoke out the tail pipe when standing on it.

I was hoping to get away with just a deep cleaning and seal and gasket replacement.

It seems like I will probably have to tear it apart and rebuild it if I want a good street runner.

All advice excepted.
Thanks