blaster motor help

[Air-cooled-R]

I just bought a +3mm stroker crank and thanks to the yamaha store, I now have a newly bored .50 over cylinder and stock style piston. I'm needing to know what octane I need to run to accomidate for the crank and if the piston will hold up. I also have some more mods done to the motor and I'm needing to know if I need to get a different style piston or if a yamaha piston will work. thanks guys.

[SYKO]

I have a 3mm stroker in my gf's blaster with a 40 over wiscoe, I would rather put a wisce in it rather than stock, make sure they bore it out with the right tollences for an air cooled motor with a wiscoe in it, I run 93 with castro 927 32:1 with no oil injection, full premix, works great!!!