One thing worth mentioning is that the T trans does not disengage. A 'sliding gear' trans separates the gears for neutral. The T model trans releases the pressure on the multi disc clutch pack. This allows for slippage when coming to rest. However there will always be some creep, or drag.
The adjustments to the park brake handle are this. Disconnect the clevis, adjust the rod to be a sixteenth of an inch short. Tighten lock nut and replace the clevis pin, secured with cotter pin.
Then, setting the handle to vertical, tighten the lever screw down 'til the clutch is disengaged.
Another thing to consider is the oil being used, If the oil being used is thick it may increase the stickiness of the discs. There are three finger adjustments if lighter oil does not improve free neutral.
Should they have loaded it with thicker oil to mask loose babbit that is another chapter.
When I got my sedan it had a slight knock at speed. Equipped with an outside oiler line I thought to check the inside oil passage. It was clogged with band material. My solution was to buy a long enough thin enough thread stock. Cut it with a bolt cutter to give a sharp end to it. Then with the front cam gear cover off, ( and radiator ) and the thread stock mounted in my drill motor I spun it into the oil passage, pushing and pushing and pushing, until it broke through the crud and reached the mag housing. After all that I had good oil flow to the front. Nice 30 wt. oil. AND, and an easy cranking minimal drag creep.