I'm thinking about splitting them, having a chain/sprocket interface to the tranny should be straight forward.
maybe a 2:1 going into the tranny
then a yz compatible 14 tooth on the front and the existing 37 tooth on the gs250 on the rear.
@3500rpm that should give me 57mph on my gs.
speeding up the ratio into the trans to slow it down later seems a little weird though.
I'll have to take a closer look and keep re-evaluating the options (and list some spare parts on ebay ) I'm a looong way from fine tuning
our motors are relatively close in power/rpm range (and torque profile).