my block is a 1980 gm 4 bolt truck block. it does not appear to have been lined bored to date. the cam does not walk too much, and to be sure, we put a button on it even though you are not supposed to need to with a solid lifter cam. my crank is a scat. i am not sure if it is from japan or china or what ? hope not. the gears appear to run straight, but the old gears have strange wear patterns since the explosion. i don't know if they were wearing funny, or maybe they were cut / machined that way , or maybe the junk chain caused them to wear funny? i only got 9 eighth mile passes on the complete rebuild, and i was shifting @ 6200. when the chain failed this time. the car usually goes through the traps in the quarter at @ 73, or 7400 . i just got a good set from cloyes, and not only does the chain look to be of a much better quality, but the gears appear to be machined correctly. i just hate to put it back together with the new chain if i am missing something. thanks for the help, and any other ideas you might have !