Glad you started this and hope it is still progressing. An awesome look at what it 'really' takes to put this together.
I was looking at an LS head cut/weld, it even has 4 bolts per cylinder like the 292. Then I laid the LS gasket on the block and everything looked good.... except one row of bots were outside the solid area of the block.
The bolt lay out of the originals does not really suite cross flow heads. The SBC head conversion sort of works around it, but the passenger side of the block simply does not have enough room for pushrods and free flowing ports. The canted push rods on your set up give some guidance on how to get around it.
I've given some thought to OHC conversion, it would not be particularly difficult on the block side, but as noted a totally new cross flow head based on LS ports with repositioned bolts would be needed to take advantage of it.
But keep on going!
