The biggest issue with the 318 is piston availabilty. Of course, at this point if you want something other than 30 year old pistons you have to order them custom anyway. Unless you like 5/64 or 1/16 ring packages. I don’t.
These days 5/64 rings are definately not what we want. Might be able to find 1/16 rings pistons. Going to 0.043", 1.2mm.or 1.0mm for a 318 would definately be custom, which would be a cost step up.
On a cost basis, the 1/16 rings would be acceptable in my mind. Only reason to use 5/64 rings is if you are reusing the pistons.