Update...
Used heads came in, got them disassembled and cleaned and they look to be good for a rebuild.
One of my Navistar blocks was cracked. Seems no one has ever seen a cracked one before. Main web. Block is junk.
Machine shop called back today and told me that 2 of the rods are cracked. Really, only 2? Because with the way everything else is going I would have expected issues with all of them. So got some used rods on the way so they can be rebuilt with the 6 good ones.
Current carnage list heading for the scrap heap -
GM 506 block
Navistar 506 block
2 heads
2 full sets of rocker arms with shafts
2 rods
Told the shop if they find cracks on the crank then I'm scrapping the engine project and dumping in a 4bt.
