Cadillac Repair: cadillac head gaskets, blown head gasket, head gaskets

Question
as a mechanic myself ive done major overhauls on just about any vehicle...i have a 97 deville..i just installed a used engine it now appears to have a blown head gasket...talking with several techs i ve heard of needing a thread kit to rethread the block when doing head gaskets...?my question is....is it a definate thing i have to rethread the block or is there a routine that i can follow in order to save the current threads..like using a breaker bar instead of impact gun for dissassembly...maybe the order of the bolts being removed would help? is this kit available from a parts store like NAPA? thanks in advance....david

Answer
According to the service manual you are NOT to reuse the old head bolts as they have a special compound on the bolts that keeps them tight in the threads. It is most important to make sure that the threaded holes in the block are extremly clean of the special compound from the old bolts before installing the new bolts that already has the special compound on the threads of the new bolts.