From a little internet searching the info I found points to this bracket fitting both 904 small block and 727 big block applications.

However when I place it on the 727 mounting boss, it sits at a weird angle rather than perpendicular to the frame rail.

Do I need a different bracket for the big block?

[img]https://imgur.com/8s5ffc3[/img]

904 and 727 small block each have their own bracket. If anything I would have thought it would have been the small block 727 one that would work with big block.

when i replaced the 318/727 combo in my 74 dodge 4x4 pickup with a 440/727, all the linkage was re-used from the column shifter.
with that said, i'm guessing [?] or ASSuming [] small block 727 passenger car 727 linkage will work with big block 727 transmissions as well.
however, i have been [way] wrong in the past, and i will be [way] wrong in the future.
your mileage will vary.

On my 67 Barracuda with automatic column shift , there is a bracket that has a stud mount with a nut that fits on the transmission , and serves as a pivot point for the bellcrank in the shift linkage . I found that if I took the stud out , and turned it around , mounting the bracket on the Bottom/ or top of the mounting pad on the transmission, it would make the linkage line up when changing between 904 and 727 transmissions . I am not sure if this is what you are talking about , or if you understand what I am saying . I am just trying to help ! Note: my car is smallblock .

I've drag race many SB automatic(both 727 and 904) Mopars.A,B and E bodies, without those tranny support brackets with no bad results

what did you use for shifters Cab ?

Many different ones including the stock one in the cars, BM chrome boxes before they were outlaw by NHRA Hurst, Winters, T/A and several others I can't remember right now
I learned that all those cable type aftermarket shifter cables needed to be adjusted so the tranny end adapter would slide in and out of the shifter arm hole easily in all three forward gears as well as in neutral and reverse

i also make sure the factory shifter's linkage slips in and out of the transmission arm holes, as i have a bunch of different arms for the valve body.
plus, i have a bunch i have gathered from swap meets that seem to come from various B&M valve bodies and kits.
you are dead on about making sure the shifter detent matches the transmission lever position, Cab.