Another Mopar Off My Bucket List - Barracuda Fastback

Can't you just elongate the mounting holes? Only 1/8" per side seems very feasible.

I remember at a machine shop I once worked , we had some 4" gas pipe manifolds to weld together, had to allow a lot of extra material for shrinkage. It was a real trial & error process but once we figured it out you could very accurately predict the shrinkage factor.

Good luck with however you decide to fix it!