Not a hope in hell of any 125 making 60BHP on gas, at least not in any way that would be useful when you take it off the dyno and bolt it to a kart. Methanol, maybe, gas hell no. Even 50 is darn close to a trophy pull anyway.
That said, on your average sprint track the 250 is going to be squabbling for grip, usually the 125s are just as quick, if not quicker for that reason. Bigger tracks its a different story. If you’re powerful in HP but not torque then you have to be spinning higher RPMs, whilst keeping torque up.
For dyno sheets, unless you know a lot of the factors behind the data it’s not going to be all that meaningful. Fuel especially and of course if the TM you are dealing with has been modified, the “stock” curve is useless. Also, you cant use the motorcycle curves for the kart application, as they generally have much different pipes.
Try Italian motors for more info on the TM moto. Very good package, IMO a better motor that the CR125, but Honda won that battle. I think of it as VHS vs BetaMax LOL.