Excessive pressure in the transmission cooler circuit can cause the converter to push the crank forward and wipe out the thrust bearing. Read this, https://www.motor.com/magazine-summary/thrust-bearing-failure-prevention-analysis/
Wow! that's a great read thanks Larry. Lots of good info I'll check as I'm putting everything back together.
Definitely want to check out the transmission and cooling circuit. Yardley once had transmission shifting issues that confounded him, and it turned out his new trans cooler was restricted. I don't think it hurt the motor, but he was pretty frustrated for awhile. When I first went to a fixed pitch transmission, and new converter, I rigged up an oil pressure gauge in the return line. Pressures were pretty low, 20-30 psi if I remember correctly. When I put the transmission in manual low and second, it boosted pressures, up around 40-60 psi. Something to think about.
I'm not running a trans cooler, but I will definitely check the circuit pressure now. I had no shifting issues before the breakdown, but...Someone has been in that trans and added a shift kit, so it might be a good idea for me to have it gone through again.
Measure the main line pressures inside the transmission. If they are excessive, it can contribute to the problem. Like I said, manually selecting gears boosts the pressure beyond what it normally is, so if it's too high already.
I see the pics now.(on tablet). If it was me I would get another block and crank. At the shop I work at the money for replacement heads and new cover has to be on the table before we start on the thing. You want it bored out? Wait on buying the piston till u hear from us. These requirements pertain to buick v/8.
Mike, this happened 2yrs ago. Larry was suggesting before I put my new build in (see: https://www.v8buick.com/index.php?threads/my-350-build-getting-closer-need-some-advice.350594/) that I check the trans to make sure it wasn't the root cause of failure. I definitely don't want to do this again!