Well, when a motor overheats badly you can score the cylinder walls and cause a loss of compression, crack the valves, crack the heads, warp the heads, and warp the block. The first thing I would do is a leakdown test to see if you can pinpoint where you are losing compression.
A loose timing chain would cause low compression in all cylinders. It is possible you wiped out some lobes on the cam.
If the heads warped, then the block deck likey also warped and would need to be cleaned up.
Lousy situation, sorry to hear you are in it. Good luck!
Hey, maybe post where you are at and someone local can help you out.