Blown turbo or hung jake?

It just popped into my head because he said it was burping when he let off the fuel after rebuild. Then turned into loss of power later. That leads me to think that maybe it was acting up in the beginning on opening. Then started sticking over time. For timing to get off after the rebuild would mean something serious happened while it was running. I would rather check a waste gate or blow off valve (if it has one) than tear into a top end.
I ran mechanicals for many years, and back then I still had to work on them. I miss it in a way, but do not in another. At least problem solving with a mechanical is easy compared with the new computer driven junk.

 

Yeah, makes sense. I've seen waste gates freeze up from non-use periods often. I first suspected a timing issue not knowing what all was involved in the overhaul. I've seen them out of time and blowing smoke clouds and I've seen them shooting fire out the exhaust so that was my first thought.

 

I drove an 82 Diamond Rio that we wedged a 600 cat in. That thing blew flames in the morning during the winter. The advance was just off when it was cold. Cleared up after it warmed up.

 

I worked on a few Diamonds, they were built like todays tanks. I miss those old trucks! Hot boxes to get baked in though! Shake rattle and roll!

 

Were you able to confirm it was the correct cylinder head for your engine?

 

you are still calling this engine a B model. the pictures you posted show C model. Maybe you have some wrong parts?