I just did the same job on a 1963
Overlander. Same windows, as far as I know.
I can post a few pics tomorrow, don't have them here right now.
Anyways, it's just sort of a bear to get the glazing bead to fit into the channel. The original was a plastic profile, very thin and rigid. The replacement is made from rubber, and the retainer tangs at the rear of the profile are just a hair too stout to effortlessly slip into the groove of the window frame.
I used a bent pick tool from a 4-piece pick set made by snap on. Here is a cheap equivalent from Harbor freight. The tool in question is the first one on the left.
It takes a certain "mojo" to get the seal to go into it's intended groove. I could do 1 window at a time, my fingertips hurt so bad afterwards.
Anyways, put the material in the inner groove, and then sort of guide the
outside lip into the outer groove while running the tool along the groove, pushing the lip down the whole time. You need to follow with your other hand and push the material all the way in. It is an annoyingly tight fit.
I used a high grade silicone spray for the job, but only spray 8in at a time, the silicone dries quickly.
Be careful not to stretch the bead. It will shrink later and leave ugly miter joints in the corners. I know....