I am a bit confused. The LE engine is from a GTA. Those GE5002 pistons are from a GT tractor with a GE engine. Getting exact match rings is going to be a matter of finding an old set. My book tells me that your compression rings are 3/16" and the oil rings are 1/4". The side clearance hopefully falls between 0.0015" and 0.003" on the compression and 0.001" to 0.1125" for the oil ring.
Ordering a new set of rings to exactly match those pistons could cost some money. Getting extra rings becomes a matter of begging as no one wants to make custom sets up any more. I order piston rings daily and sometimes I order two sets of rings to get what I need. Two sets normally are cheaper than ordering extra rings. You could just toss in some of the old rings to fill in. I used to do that too.
The reason they used two oil rings is because the one piece cast oil rings just sucked. The grade twenty compression rings were not much better. They ate the cylinder walls at a fierce rate. My advice is to call around for some aluminum pistons. For me; tossing iron pistons generally is the lowest cost alternative. Aside from EE pistons for an R; Moline pistons are not that hard to come by.