[Little]

Not an export by any means, but worked on Cummins and Cat engines for near 50 yr. If the oil analysis come back good I would take the bus out on the interstate and put it to work, get the exhaust temps up.
Hard to tell from video but your 'smoke' looks like steam. If its coolant the analysis will show it, if its smoke then you may be able to loosen up the rings by driving it. Sometimes excessive low speed driving, idling will cause this.
I believe that vintage 60 series was one of the best engines ever. Good luck. Mark