Are the freezeplugs out of the block? Check the cylinders, Mine happened to be the "cloverleaf" type cylinders that were much stronger. i.e. The Outside Diameter of the cylinders (Water Jacket area) weren't round but kind of "square" with extra material. I noticed this when I removed the press in block plugs and installed screw in plugs.
$850 for that block is a bargain IMO! I'll trade you some msc. 385 racing parts like dizzy, mini starter, alternator pluse a bunch of old FE stock stuff for it :wink: