The Maxter MXO is a great engine, but old and not as supported as TM (availability of spare parts as Maxter has not been around for 6+ years now, if I recall correctly) whereas for the TMs most of the parts are interchangeable across versions and years so it’s all available so if I were you, I’d go for the R1. 10C would be a value option, a lot less money to purchase and very little performance difference. 10C and R1 always look for a factory prep engine, they are very good out of the box.
Gearboxes have no issues and there is little that can go wrong in both brands. TM is the most logical choice for support/practicality only, nothing wrong with Maxter. Holzner and Witteveen worked on that program, high caliber engineers, those engines are valid
KZs in general cannot be stored vertically, unless you drain the gearbox
Every 3 hours I change gearbox oil (cheap)
Piston 6 hours, if you are just lapping it can go to 8. When you do top end, check reeds as well. The OEM will last a long time, usually 12 hours no problem unless you use insane advance or downshift like a madman…but keep checking them half a way through piston life. Piston brand use OEM Vertex if you can
Bottom every other piston, so 12 hours. Change crank seals, and rod pin/spacers/roller bearing on the big end. Rod will likely be ok to reuse if there is no sign of wear, otherwise replace (you can usually run it 18+ hours no problem). Bottom bearings I usually change them by default at 12 hours for precaution, but they can last much longer
Set your advance at 1.6-1.5 and don’t go stupid lean on the jetting, and you’ll be fine. Oil Elf HTX 909 or 976 at 4%. Leaded fuel is best, not healthy for you but healthy for the engine
Also, gearbox doesn’t need maintenance, other than regularly changing oil. At 12 hours when you take everything apart, inspect the dogs, forks and desmo for wear, should barely have any.
Just keep up with the oil changes, every 3 hours is a good practice.
Clutch, same thing at 12 hours inspect baskets, rubber isolators and change the oil seals. Important thing is to never kill the engine with a gear engaged, always pull the clutch as you slow down and let the engine die. Disc life depends on how much you abuse them, repeated launches in short succession is what kills them, as heats builds up