Generally speaking the curve in the distibutor will be pretty close to what your looking for with a stock cam. Your just not gonna see much of a gain by having a exotic curve with virtually no mods on your motor.
I wouldn't worry about what the mechanic said, just let them install it and time the engine and when you get it back you can make any necessary adjustments you want by changing springs or intial advance etc.
He might have his hands tied I.E govermental pressures and penalities for foolling around with a emission controled vehicle anyway. Goodluck, Charles