The old tired motor probably needs a rebuild, not just rings. If it had good compression in the first place, we could assume it's a healthy enough starting point(as long it does not burn oil and make bad noises.).
Trust those who have had their hands on junk like this before. You might get lucky and just need rings and some honing, but don't count on that being the only issue.
You are pulling the motor out anyway, so check everything and make sure your tolerances are within spec. Get the short block assembly in good shape before you start bolting on go fast parts, because doing the job twice sucks sometimes.