You should do underpiston smoothing.
It’s helpful I swear.
Just put piston at bdc and then smooth around the wrist pin leading into the 3 transfers.
So much mix is under the piston so by smoothing the transitions it just wants to flow like mad.
Also throw a big carb on it. I’m running a 21 on my stock cyl reed conversion. Runs cold and very fast.
I also love the high comp derb 50cc head. So much squish! Runs cool as well.