Art Carr 200R4 confusion


Car Audio and Electronics guy.
So when my original BRF broke ( no reverse) rather than do the right thing and get a CK trans, I bought a fully rebuilt fresh Art Carr Trans "out of a 9-sec GN". It was from a "friend" (not a GN guy in his defense) and half the price. The code read AA but it's got the billet servo, hardened input shaft. The pan was beat up (from being moved around my shop for 2yrs) so I decided to reuse my old one. Except the one from the AA would not fit on the BRF. Should've been red flag right there. But no, I proceeded. I really just don't like how it shifts. 1-2 is firm on light throttle, and 2-3 is ok. I really don't even feel 3-4. It has only 300miles of light use and I've only stomped it from a roll, which it burns out through 3rd anyway.
I just ordered the Superior (K2004 HP) shift kit. Would I be better off installing that stuff in my BRF valve body and then installing it in my fresh trans? Or should I just install the BRF valvebody and leave it alone? Or will the Superior kit correct the valvebody in the AA?

What is this 3rd gear switch in the BRF necessary for?

Sorry if my questions are stupid, I'm not a trans guy. And yes I've watched multiple videos on the detent cable adjustment. I'm 99% sure it's hardware. I want to get the problem alleviated while the trans is still fresh to prevent damage.

Thanks in advance for the input!
really hard to know what you have now that it has been "goofed" with by others before you got it. I'm not sure what this "superior" shift kit includes , so I don't know what it might do.
I am using an AA code in my car now and I like how it is shifting but we made some DIY mods while we had it appart. Swapping springs, putting in larger boost, rev boost and 700r4 spring, hard rings and sonnax spring in the slide, some plate hole "adjustments".
I can send you a list of what we did if you want. Pm me an email.
I would probably swap your brf vb and gov over to the "new" trans but without the pump stuff(larger valves and spring) you wont have the higher internal pressure if those mods weren't done to the pump.
I'm sure there are guys on here who have other suggestions. One thing I have found is the isn't one right way to assemble a durable 2004r but it does have to be done with attention to detail.clearances are CRITICAL.

does your vb have a paint marking on it like the one in the pic? Is it an AA? Or something else?
the guy I bought the trans from was a friend of a friend, and seemed like a solid guy. The issue is I've lost contact with both, so I can't really get exact mods. I know he did something with the pump and pin you mentioned, and it has the Kevlar parts and hardened parts. It had a transbrake, but I had him remove it since I wanted a lockup converter and i'm going for a 12-sec street car, not a race car. I'm not really questioning its durability, but I just hate how it shifts no matter what I do with the detent. Right now at 1/4 throttle I think it goes into 2nd at around 20mph? It feels good. I'm sure if it didn't burnout when I stomp it, it would chirp 2nd no problem. The issue is 2-3 isn't super snappy and 3-4 I can't really feel at all. The Superior kit includes a bunch of upgraded springs and a .471 boost valve. So maybe I'll install that stuff in that BRF valvebody then just drop that in the AA trans?
As far as your photo I haven't really "looked" at my trans before to notice any stamping.
What is the 3rd gear switch and is it necessary on a GN?
Thanks so much for all the input so far. I really appreciate it! I'm finally getting my project done after 16yrs and learning as I go. I'm sure this won't be the 1st mistake along the way(y)
a stocker with some traction and extra boost should run twelves if you can get it shifting well.

I would skip the .471 and go with the .500 boost valve. Get the one with the orings to control the pressure loss. A .283 rev/boost valve and the 700r4 spring. I can say if you give d husek a jingle he can set you up with this and the other parts you will need. I think if you get the pressure up it will help a lot.
I will say that if the 2-3 shift is sloppy you are probably in for at least pulling it apart and getting the direct clutches squared away. Possibly replaced but at least taking up some of the excess clearance.