can piston/cylinders be repaired? If so, what is cost?

Yes, it can be repaired, but this is a major job. This would require an entire engine tear down. Major cost. I can't even begin to estimate what a garage would charge for this.

have it checked. You're still don't know what it is. Could be a syuck valve, not such a big deal

How do you know it has a bad ring? Of course it can be repaired- but you are looking at the engine coming out, the pistons coming out, new rings- then while it's all apart, might as well do the rest- new bearings, water pump, starter, alternator, hoses, radiator- etc. etc. somewhere around 5 grand- to 10 grand- cheaper to just buy a new engine from Chevy- nobody rebuilds things anymore- just get rid of the car like everyone else does- if you want a car that is meant to be rebuilt, you will have to go back to the 20th century-

What make you think you have a piston/ring issue?

I have Impala SS how much would it be to put a cylinder put in there also a duralast