1963 Ambassador 327 auto transmission question

Hi everyone, new to the forum, been lurking around for a while but finally decided to join. A little background: My Father, brother and I as a hobby, like to find old, forgotten cars that haven't been on the road for years, buy them and get them back on the road so they can be enjoyed by either us or their next owner. Its a fun rewarding hobby. Now onto the issue:

We came across a 1963 Rambler Ambassador 990 that hasnt been on the road in many years. All flat tires, filthy but surprisingly low/no rust and pretty complete. We couldn't watch it sit there anymore so we finally made an offer and were able to get the car. Its a 327 2bbl, power steering, power brake, air conditioning car. Its an automatic ON THE COLUMN.

We contacted the original owner(2 before us) and long story short, he said he rebuilt the transmission but put the wrong valve body back in and never bothered to put the correct one back in. So he says that it will run, but putting it through the gears will do absolutely nothing(havent yet checked this for sure, but the previous owner had taken the drive shaft out to tow it home and never put it back in)

We are going to drop the transmission pan, but the problem is that we have no way of validating if it is the incorrect/correct valve body. My understanding from looking around this forum is that these transmissions, the flash-o-matic, were Borg Warner 3 speeds, BUT the internal components of the automatics on these cars differed from the column shift and the floor shift models, so 2 different valve bodies? The wealth of information has stopped here, as I couldnt find anymore information onloine or in the 63 service manual. So really:

-How can I validate the if this is the correct/incorrect valve body?
-If it happens to be correct, how can I know if the valves/springs/balls etc are in the correct locations?
-If I needed to locate the correct valve body/plate/etc - is that something that can be done? Because I don't see a whole lot of parts for these cars

Anyway, thanks for reading if you made it this far! We really appreciate all the help and really just want to see this unique car back on the road being enjoyed.

Column shift models were called "Flash-O-Matic", floor shift models were called "Shift Command". If the valve body bolts up and the trans works I wouldn't worry about it. The FOM shifts different that what you're used to. The first Drive position (shifter should have a D with a 2 between D and N, a 1 between D and L) the trans starts in second gear. A lot of people think they have a two speed trans. Pull it down to D1 and it will start in first gear. The reasoning for the second gear start was that it is better for slippery surfaces such as snow and ice -- less spinning. The SC trans works exactly like most modern trannys -- P R N D 2 1. It can be easily manually shifted through the three forward gear.

I think the PO may not know how the trans was supposed to shift. The VB may have been changed from another trans, but if it fits and works it's the "right" VB. Other models won't interchange, has to be a similar model trans. The M-3x (35, 37) and M-4x (40, 42, 43, 44) may interchange, and the M-11 and M-12 models may interchange, but IIRC the M-3/4x and M-11/12 won't interchange, and I know for sure that the older M-8 and M-10 used a noticeably different VB than the newer M-3/4x and M-1x models.

This may sound stupid but have you verified that the shift linkage is even STILL HOOKED UP? Or has loosened to the point of no longer moving the throttle lever down on the tranny.