Compression check is not going to give you much info if the engine is worth rebuilding... other than if it NEEDS rebuilding. Good compression could still mean bad valves, worn journals etc etc
Do a good visual inspection for obvious cracks around the cylinders and valve seats. Then look over the whole motor to see its in good shape.
You'll need to take it apart and get the head/block magnafluxed and pressure tested and the crank/cylinders miked to see if its actually rebuildable. That's a $300 work order.
You could ream the cylinder, put in new rings and hope everything else is ok... you might have a runner, you might have a boat anchor.
