If it is the same as my '41 they are straight cut and actually mesh gear to gear. Double clutching is always required for both up and down shifting. Once you have mastered the art of matching the engine speed to whatever it should be for the gear you are going into it is easy to shift even without the clutch.
And yes the straight cut gears wine all the time (except high gear) which is a straight through drive putting no load on the gears. There should be no grinding once you are in a gear and hopefully none during the shift, but then, shifting is an art and somewhat complicated by trying to keep the truck pointed in the correct direction without power steering.
As for advice, don't plan on doing anything quickly.
Good luck with your new ride
Kip
