Joe,
The Super Ringmaster is a pretty decent sport airplane if kept relatively light. I had tried to build one from a kit a number of years ago, but was pretty disappointed with the leading edge machining and weight, so ended up building an entire wing from scratch for the same weight of the leading edges alone. It is similar to the S1A, which has a built up leading edge. In any case, it is moderately heavy but still a decent flyer if you don't lean on the controls too much in which case it tends to stall a bit. I am using an FP 25 for power and it seems to pull it around fairly well. The LA should be a decent match. One thing that I am not too hot on is the short ground clearance.
Since it sounds like your airplane is already built, focus on trying to get it to balance in the proper spot with the least amount of weight you have to add erring to nose heavy (for proper turning and stability). Hang it on the front leadout and make sure that the nose points a hair down (for proper line tension). Then take it out, half tank it or less if you have a clunk style tank and send it up for a few laps to get a good feel for it. Mine flew pretty well as shown on the plans, but it was a bit nose heavy with the standard muffler. It was replaced with a tongue style muffler and flew better due to improved balance and less weight. Again, not a full bore stunt ship, but it flies a relatively decent pattern.
John
Shameless plug: I have tongue mufflers available for $20 plus shipping for the OS 25s (LA and FP)