OK, hold on. What exactly "blew up" on the engine? Did it throw a rod, blow a headgasket, or what? Does it still start/run?

"most people when they rebuild they have to worry about measurements... the measurments of the pistons, and the bore, is it out of shape. Well you could go with new pistons for $500 dollars so no need to worry about the measurements and getting the right sized rings. You could also put in new sleves. So the pistons and new rings will match the new
sleves."

Yes, you MUST pay very close attention to measurments if you want it to run right when your done. It's not just "throw in the parts and go". The liners must be honed to match the pistons + oil clearance and there are many more measurments, torques, and clearances that must be used. Reading the Factory service manual cover-cover is a MUST before you open up the engine.

But, first and foremost, I'd track down that "friend" for some compensation (Money or otherwise). Sue the bastard if he/she won't cough it up.