Magnum Swap column vs. console shift

64? should be a 904. Is it a cable setup with the center console? just like the push button shift. Mopar Push-button transmission tech tips
If so all you'll need to do is fab up a different cable. Or modify the cable end. the 904 with cable shift is internal in the trans unlike the 46RE
I would be surprised if you had a 727 in a 64 unless it was already a swap. In order to fit the 727 you would have to fold the pinch weld where the trans tunnel meets the fire wall. In order to fit the 46re you need to do alot of massaging of the tunnel and some chop / cut -n-weld for the overdrive unit... lol fun fun...
I have a 65 and I'm doing the same 46RE. I'm using the center console shiftier that's a cable shift.
If you scroll down page 4 you'll see what i'm working with...
1965 Barracuda MMP

Hope this helps... If you need any more info on this hit me up.
Good luck with the build...
Thank you so much for the input. Very excited, just found a donor vehicle (97 Van, 360 magnum, 46re)!

I've been offline for a few days but was happy to get some tips. The guy I bought cuda from told me it was a 727 but you may be correct that it is a 904 (lesson: assume nothing).

I do have the overdrive mount from the donor and I'm hoping I can modify this and it will give me a head start. Fitting this 46re should be interesting but crossing fingers that it's worth it.

I'm really impressed with your build, custom intake and efi, very ambitious and fun! I'm going to study your posts.

I'm also curious as to what alternator your going to use. I'm hoping to use the stock alternator that's already with my magnum donor.

Thanks for the offer for assistance I may take you up on it. Cheers,
Rob