1st gen Big Block Crossmember

[beater68427]

I'm wondering how far exactly did gm move the mounting holes to the right on the Big Block transmission crossmembers, what would center to center from the old holes to the new? On the beater small block mounts were used I needed new headers and they would not clear (old ones did) so I decided to go with bb frame mounts, and instead of buying a repo crossmember I am just coing to cut a rectangle out of the crossmember offset the center to center distance on one side and turn it around and weld it in, versus just cutting holes.

Thanks in advance