No need for a governor if the trans has no method to shift automatically with a manual valve body.

It does nothing. Just another part to remove to eliminate the chance of having any issues and a tiny bit of weight loss.

I also run a 505ci in a 70 Challenger with a 3:55 gear. Here is my 727 modifications:

Stock front drum with 5 thin Alto Red clutches and Colene steels
Modified rear drum with roller bearing 4 Alto Red and Colene steels
Billet rear support with roller bearing
A&A super sprague
Billet front and rear servos
Billet band struts
Turbo Action manual valve body forward pattern LBA
Aluminum deep pan
PTC 9.5" converter 3000 stall

No problems in 11 years and I built the trans myself with the help of the late Carl Monroe's book

Call Bobby at Reliable Transmissions in Waterford, on Dixie Hwy.
248-623-2230 ...He is a race car builder, and knows his transmissions.

You have a rebuilder and you are asking on this forum what is wrong with your trans?

You need a new rebuilder. He's the one that should be diagnosing your problem.
And fixing it. It's not your shifter.

Now why would I go back for the third time? How many times do you get kicked by a mule before you realize it hurts? I'm not taking this trans out again so I took it somewhere else. Yea, the original guy has a warranty but what good is it if I have to keep taking it out?

I can relate VERY much to what you say,That stuff set me back 2 yrs in my goals.

ok- if you aren't going back to him again - then you are on the right track. If you want it fixed correctly the First time PM me and I can get you fixed if you want.
Sorry - just saw you took it somewhere else.