[mr48chev]

Back in the 70's a buddy of mine built his own engine stand to hold up the 426 Hemi out of his Roadrunner. He drilled the bolt pattern of the bellhousing mounting surface of the block on a piece of 1/2 inch steel plate that was big enough to cover the back of the engine and then welded a piece of heavy structural pipe to it to stick in the stand. He had a cut out for the crank. Rather crude looking but he was the best welder in town and it was strong.

If you were to take a piece of 1/2 inch plate ( I don't think 3/8 is strong enough). you could cut out the inside of the pattern of the back and drill the holes in the right spots to bolt it to the block and then drill 4 holes on the corners of the plate to bolt to the arms on the stand. That would probably take going to the scrap yard that sells remnant pieces rather than the steel yard.