Hi guys, I need to borrow some of your knowledge.
The case is this: looking to stock the sleeve/piston/rod for when it's time to replace on my Argus A52 but it is hard to get replacement parts for it here in Portugal, and the few places that do sell them awfully overpriced. I read somewhere in this thread that Alpha sleeves fit the A52, the only thing needed is to dremel the slot on the opposite side in order to rotate the sleeve 180º, so no problem there for me.
My question is what sleeve would be more identical to the A52: the A852 one, the A872 one or the F850 one?
From what I could gather, the A852 would be the one, but I would prefer to hear from someone who has owned or at least compared the two.

By the way MrHavana, from your pictures your engine seems just fine and no pitting is seen.
I ran the A52 about 4 gallons with Ammo 30%, one .2 shim and OS P3 plug - believe it or not, that plug lasted all the way from break-in to the 2nd gallon in racing conditions.
Fuel wise, it is by far the best fuel I have ever used (and have tried quite a few), the oil percentage is just right, the temps are 10-15º lower than what I have experienced with other fuels and the power is amazing, so I strongly recommend it instead of whichever brand 25% you were trying to decide.
And while .2 shimming might be on the low side for 30% fuel, I did not experience pitting or overheating so I'll stick with that, with .4 I believe you are loosing valuable power so I would consider .3