That's why I recommend cutting the webs. I even stress relieve the manifold by baking it in the oven at 500 for 12-20 hours, then a long cool down, THEN cut the webs and have the gasket surface faced back flat.

There's a stud welder made for MIGs that has a hollow stud for the mig wire to feed thru. Just put the stud on the gun, zap it to the broken stud, and you have about 75% of the original strength back. Muffler shops love 'em....

Not responsible for advice not taken...