It seems that I have the following options:

1.) Bore size .010 over and custom diameter pistons and shelf rings. Rings available only in 5/64 (pre gapped)

2.) Bore size .020 over and custom diameter pistons and shelf rings (pre gapped and file fit available) in 1/16

3.) Bore size .030 over and shelf diameter pistons and shelf rings

What's more important (option 1 vs 2) - wall thickness (.010 vs .020) or ring thickness (5/64 vs 1/16)?
I'll have to order custom pistons anyways (will be a dished piston) the price for all three options is pretty much the same.