Even modern shutters are frequently slow at 1/400. You will probably never want to use that speed. With typical taking apertures of f16 to f32, you will find yourself rarely using speeds faster than 1/60. A repair cost of about $40 seems pretty reasonable. Another approach would be simply to write down the actual speeds and use those values rather than the values marked on the shutter. This will work as long as the shutter is consistent. It depends on your desire for a newer lens vs the thickness of your wallet. In either case (this lens or a replacement), you will need a lens board.

With a predrilled lensboard and the inexpensive Toyo wrench, it is an easy job to mount the lens. The Toyo wrench is very reasonable and works about as well as much more expensive wrenches. The difference is that the Toyo wrench is a metal stamping made to do only the standard size shutters while more expensive wrenches are continuously adjustable.