727 not shifting right

I haven't had much experience with manual valve bodies so I haven't seen everything but if it had a governor plug installed wouldn't that prevent fluid from reaching the governor? If so wouldn't the governor pressure always be at zero? If that's the case it'd always stay in low gear. Someone correct me if that's wrong

They block off the governor on manual shift valve bodies because they use a manually directed oil flow to apply gears.
The valve body is designed to where all it does is redirect flow from one set of internal parts to another set to change gears without any effect from driveline speed at all, so the governor is pointless and therefore blocked off or removed completely.
Probably removed completely if it was professionally built for racing, and in that case the plug would HAVE to be there so line pressure wasn't lost through the open passages where the governor was.