What about a gp1200 motor. HA
You will still do better with the Dasa motor & you dont have to re-invent the wheel, like engine mounting, tripple pipes & no room to swing a cat in the engine bay.
A stroker crank in 61X cases will make the situation worse, by increasing the volume of the motor, which needs more gas, but the cases & tiny reeds won't be able to deliver it.
I've ported 61X cases & they make better power, but no matter what you do to those cases they will never perform like 62T ported cases can.
If you wanted awesome power & were thinking stroker, an 8mm Dasa, ported 62T cases & Powerfactor Pipe will blow your mind & launch you off those waves into next week.
Your seat is looking trick!