Unless you use a dial bore gauge to verify if the bores are round and that they are not tapered, you may be wasting your time putting rings in it. If the bores are straight and round and not worn to the point of needing to be bored, you may get by with honing the block and putting in new rings. If you have never built an engine and can't take all the measurements, pull the short block and take it to a machine shop that knows Buick V6's for evaluation.