Someone with more experience than I will surely respong, but here's a couple starters.

Two head gaskets will NOT work, don't go there.

Look at the block deck between the PS pump and IP to make sure you can see the engine number, a good indicator that your block has not been machined- it should not have been.

Not sure how successful (or even possible) decking a head is on one of these. Too many issues of clearance involved. Not to take advantage, but I have good head for sale. Others will as well.

Last, did you check piston rise above block deck to ensure no bent rods?

__________________
Chief

1991 350SD