If it where me doing the build, I would set up the motor for low/mid range power. I don't know how experienced your wife is on a quad, but there is nothing like putting an inexperienced rider on a toggle switch motor. What I did for my wifes bike (That I just blew up lol) was a mild port in stock cylinders, cool head, V3 reeds, T5s and a lockout with a MSR, so I could keep the stock springs/easy clutch pull, and be able to hold 60hp. I wanted to make it so she could enjoy longer rides, and not be fatigued.
I think the next build for my wife will probably a 4mm serval, with paul turners on it.