I have a 1980 Firebird with a big block Chevy in it. The car originally came with a 301 Pontiac v8. When they installed the big block they just welded the clamshells right to the x member. The holes in the clam shell don't line up with the holes in the cross member. I would like to redo this and install mounts that would bolt up using the original cross member holes. Any ideas?