T 10 transmission 66 mustang swap

[Preston]

I just installed a fresh 200 engine in my 62 Ranchero, and used a T 10 4 speed transmission that was left in a shed that i know nothing about. The side cover had been removed and reinstalled, so I had to locate the ball bearings in the bottom of the case and get them back into the shifting pall. the transmission with new clutch pressure plate and throw out bearing is installed in the little truck, Im using the origional floor shifter thats still attached to the unit. I have cleaned everything up changed the seals etc. my issue is when adjusting the shifter i can either get reverse and no first or first and no reverse by turning the shifter tang from pointing up to down. Also does the reverse mechanism inside the case supposed to have a ball between the lever? the shifting stems seem to be blocking the full engagement of reverse or first on the outside of the case, When I have it set to work in first, reverse is to me and back (with the shifter) its grinding not moving back far enough to fully engage. I know these transmissions were used in the 60's in just about everything just checking to see if anyone has had this problem, this is a side loader not a top. I have driven the truck and its shifting fine stays in gears no popping out or any other issues.
Thanks for your help, I have come to a dead end just thought I would seek some help from the wise ones