Shoot it. It was made to be used. Stick with low pressure loads only because it is a vintage double that wasn't designed for modern high pressure loads. But remember that recoil is what damages old brittle or punky wood, and recoil is not a function of pressure. Recoil is increased by higher velocities and/or heavier loads of shot.

Measure your cracks and run a case of mild loads through it. I'll wager the cracks probably won't reopen or get worse. They probably began years ago when someone's pounded the piss out of it with heavy high velocity loads. L.C. Smith's I've owned that had cracks behind the lockplates never got any worse with conservative loads.

I am interested in how your gunsmith did the repairs, and why you think his repairs are prone to failing. Cyanoacrylate or crazy glue will help stabilize fragile old wood, but it won't be as strong as either good wood or properly done glass bedding. Wood needs to be clean and free of oil soaking before cracks are repaired, or no kind of glue is going to do a good job. Soaking oiled wood with cyanoacrylate is only going to make a proper job a lot more complicated. Amateur and professional gunsmiths should follow the same Hippocratic Oath as Doctors... "First, do no harm."

A true sign of mental illness is any gun owner who would vote for an Anti-Gunner like Joe Biden.