Piston rings question

[CrazyCloud]

Looking into rings for some mystery pistons I am using for a project. They are 69.5mm rings, 1.5, 1.5, 2.5mm. Most modern rings are a bit thinner it seems. Total Seal said they could help me out, will require some minor machining of one of their rings, and widening oil groove on my pistons. The question is: the ring grooves in the pistons are 3.4mm deep, and the Total Seal rings are 2.56mm radial depth (.84mm difference). That seems like a lot a 'back clearance' behind the rings to me, but they say they will work fine. I have seen minimum specs for back clearance, but not maximum #'s. Any engine builders/others have experience with this? I am sure Total Seal knows their stuff, just looking for reassurance...
Thanks!

[GregT]

They'll work fine. I'd have probably looked for a car set in that bore size and widened the oil ring groove to suit what I could find.

[gs11ezrydr]

In the back of a Wiseco piston catalog is a ring chart with all the sizes and different size rings that are available through them. They have all the sizes etc. listings like XC'XA, are what they are called .Ck. with Venolia ,Ross, MTC, etc. There is only a few piston ring manufacturers and most companies use there rings. Unless you have a custom piston and ring set I think you could find some or even have them made to your specs. Have you checked these pistons to make sure they are in good shape. like measuring them not just how they look? in order to go through all the trouble and cost to find rings that will fit some slugs that aren't worth running. Just a thought. May cost you more then buying a good set of known pistons and rings. Have you thought about the proper circlips for the grooves in the pistons, or even piston pins that fit properly and that are possibly not worn. Your Mystery pistons might be just that a mystery too all.. With something current and well known there will be no problem with replacement parts also. Just my ideas and thoughts.....