5.7 E-body OD tranny options.

I'm just wondering what the best options are for an automatic OD transmission for a 5.7 in an E-body. I have a 545RFE out of a pickup, but it has no provisions for a speedometer and is considerably larger and would require the cross member to be cut out and refabricated. Is there a better option that would be speedo friendly and require little to no fabrication, or is that going to be unavoidable?

A518, 727 + Gear Vendors

One more for the list. The Silver Sport "A41".

https://shiftsst.com/articles/cat/mopar/post/challenger-barracuda-1970-1974-perfectfit-kit/