727 Installed - No Movement in Gears

Hello! As the title states, the car doesn’t move or react when put into gear. 1968 Dart, 1975 727. I installed a trans-go shift kit before installing the transmission, so there’s always the possibility that I screwed something up there... it was my first time. Here’s some info:

- B&M shifter shifts the transmission into each gear as it should, confirmed by crawling under the car and watching while someone went through the gears. Each has a positive click.

- TC was seated properly, had to be pulled forward a small amount to mate up to the flex plate.

- With the rear of the car jacked up, the wheels spin gently when in gear, but very light brake pressure stops them. Applying any amount of throttle (up to 3k RPM) with light brake pressure will not spin the rear wheels. From what I read this seems normal? However, the wheels also spin gently FORWARD when in reverse, same as in other gears... if that matters?

- I installed a +2 quart deep pan, so I figure the transmission should take somewhere between 10-12+ quarts total. One problem I see is, I added 8 quarts (1 into the TC before installation, then 7 more once the trans was installed), and the dipstick shows full. I know it shouldn’t be full with 8 quarts. I have let it idle in each gear, so the TC should be filling and requiring more fluid, but the level is not going down. I’m checking the fluid level in neutral while idling and hot.

My next plan is to remove one of the trans cooler hoses (I went with stainless braided with 6AN fittings) from the trans cooler to see if fluid is pumping while running in neutral.

Should I add more fluid? I accidentally dumped about a quart out when I changed dipsticks, because I wasn’t sure if my new dipstick was reading correctly, so there are about 7 quarts in it now. That’s up to 5 quarts “low”, but I figure it should still do SOMETHING with 7 quarts...

Thoughts? Thank you!