Sincraft...I wouldn't worry too much about whether or not you've damaged your engine. You're obviously happy with the power it has when flying so that's good. If it starts easily (by hand, electric starters cover up a multitude of sins) then that's another sign it's in good shape. Turn it to TDC, preferably when warm, and see if it holds compression for a reasonable time. "Reasonable" in the old days with cast iron pistons was at least 5 seconds. Take off the muffler and have a look at the piston for score marks. The chances are that there's nothing wrong with your engine.

Although there's a correct way to run these in, so long as it wasn't abused (even if unknowingly) then the difference shouldn't be anything to make you lose any sleep over. But to keep it in good shape then I'd suggest using at least 20% oil (and more certainly won't hurt) with half or more of that oil being castor. If it's a plain bearing engine then it definitely needs that amount of oil (that goes for all bushed engines). As for the tune, you can never run these too rich, it's the lean side that causes damage.