I'd run whatever the stock recomendations are and let him figure out how he likes it set up ...... Arctic Cat has the "factory default" shock pressures published in the user manual. I wanna say for an M series it's like 65 psi up front and 115 in the rear.
I'm running 75 psi up front and the max of 150 in the rear, but I'm ~300-lbs ride weight .... I'm probably gonna send my rear shock off to be revalved at some point.