Option One is to have the stock cut off and a new pad installed.
This would likely be the best, since you can buy one of the new super-recoil pads that Remington is using now.
Any gunsmith can easily cut down the stock however much you need and install a new pad.
Option two is a possibility. Remington used to use checkered aluminum butt plates on the 742 rifles. Possibly one of these would fit, but no guarantees.
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Option three is to buy a 1/4 inch thick brass plate and make a plate. You'd cut the rough plate out with a hacksaw, drill and counter sink the holes, then file to the final fit.
Option 4 is to buy a "youth" stock with pad. These are shorter, and are often used by combat shooters since the factory stock is too long for this type of shooting.