I'm also racing on a J/125 right now. It's one with the un-reinforced mast and the checkstays are essential for shaping the main. You pump up the backstay to get headstay tension but that inverts the main, so then you grind on some checkstay until the main looks right again.
This could also work on the 92 for a long, breezy upwind leg, especially if you have a main that's too full or not cut quite right for the mast bend (as many of them were). Mine were runners but checkstays could be helpful in the right conditions. I wouldn't throw them away until you've sailed the boat a bit.