Cheapest piston rings for ATC 90?

[MastaFlyMason]

I have an ATC 90 still has the original piston I am looking for a new ring set (I guess that would include the oil rings and such?) as cheap as possible. I found one that is .25MM OS for really cheap, could I just file the rings down to the proper gap and install?

Thanks!!

[MastaFlyMason]

Scratch that I found the rings, what gaskets do I need to replace? I found the head gasket, do I need a base gasket as well?

What all should I buy besides the piston rings?

[Samjp22]

Since the heads coming off it's best to replace the base gasket as well

[cdrookie]

once it's tore down inspect the bore and piston. i know they are relatively low rpm motors but your 90 has many years of use on it and who knows if the air filter was regularly clean.