Looking for some input and thoughts on a dilemma with my big block 727...

Just the other day, after pushing my car forward in neutral about 15 feet then later attempting to reverse the car, it felt as though the wheels were chocked or the brakes were applied. Forward was okay. I drove the car home (no noises) and attempted to reverse and noticed it felt the same way in reverse. I would go forward a bit and be able to go in reverse a bit and needed to go forward again to be able to reverse some more. After a couple of R to D to R cycles it would stop reversing and felt locked up.

Initially thinking it was something to do with brakes I disconnected the driveshaft and isolated the concern from the trans.

The transmission is a BB 727 built years ago by B&M and has a reverse manual valve body.

A little brief history, when I first drove the car/trans I mistakenly shifted the trans back into first instead of 3rd from 2nd gear at approx 50mph. (driver error and column shift car).
I blew out the rear yoke straps and all had been fine since then.

Now looking at the service manual I see the low and reverse share the same band.
I dropped the trans pan today and see what look to be pieces of band material in the pan. I am thinking my low/rev band is toasted. Am I correct?

If so, can I sneak the band out by dropping the valve body? I remember a friend of mine telling me one of the bands is able to come out with complete teardown and not sure if it is the low/rev band or not.

Any thoughts and suggestions would be greatly appreciated!