LS1's are actually 346's.

umm right off hand i do not think so. reason i say this is, LT1 was reverse flow cooled, so that allowed them to open the envelope on using higher compression. the reason the LT4's have high compression is the fact they have a smaller combustion chamber in the head. stock compression is 10.4:1...if he wanted to cut the heads a little he could bump the compression slightly. personally, if he is going to do a stock rebuild, i'd recommend summit, as they have rebuild kits for about 500-700 dollars that include everything to rebuild the motor minus rods/crank basically and you can choose among some pistons if that was really what his goal was. personally 10.4:1 is fine, he isn't going to be running alcohol or anything in the future that i can tell so what he has is fine. if the turn the crank though, he might be able to get an offset grind and pick up some cubes...but i dunno if it'd be worth it for him or not.

for the price he'd spend fixing that thing up, he could probably find a fair mileage LT1 somewhere for cheaper.