Your gunsmith doesn't want to. I've done many 742/7400 trigger jobs including my own. You can work the factory parts or use aftermarket parts from Timney available from Brownells. I have one on my bench right now I'm doing a trigger job on as soon as the Timney part arrives.
If you will call me I will explain how I solve the Remington 740,742,750 etc trigger problems. I can make that trigger work like a jewel! NO TAKE UP, NO CREEP, NO OVERTRAVEL. JUST EVEN PRESSURE AND THEN BANG. I EVEN PUT AN OVERTRAVEL SET SCREW IN THE TRIGGER GUARD.
I have done over a hundred in the past thirty years and what I do makes a completely new trigger out of them. They are not necessarily a shotgun trigger at all. Remington designed this trigger group to fit many guns in their lineup. When I am done with a unit it has a set screw installed from the rear of the guard to stop overtravel, about 75% of the trigger movement is eliminated, the trigger is shimmed to eliminate any wobble, the engagement surfaces are stoned to give a smooth non gritty pull and the weight is set to your number. I wont take one down to less than three pounds for a safety issue. It completely changes the who charactor of the trigger and finishes what shoud have been a great trigger to begin with.