Welp... I looked at the other door (OEM strip) and discovered I'd installed the replacement strip incorrectly. No wonder it looked so "wrong". So I removed the glass (disconnected the channel from the vent window and slid it out the top). Then attempted to compress the sides of the strip and get it into the channel from the top. I ended up boogering up the end of the strip and it won't fit with the new, thicker nylon slides either.
It will
just go in with the original slides.
I think I need to start over with another expensive piece of plastic. Don't know whether to try wrestling with another reproduction, or hope I can find a 45 year old original that won't crumble if I look at it wrong.
Also, I could use some advice on the proper way to remove and reinstall the window & strip. I'm thinking of removing the channel from the door entirely, putting the glass/strip into it, THEN sliding the assembly back into the door. Probably how I was supposed to do it in the first place?
Edited to add: I should have done more homework first
A search of Moparts found this handy FSM excerpt posted in 2011. Looks like I should have taken the whole assembly off the door and THEN worked on it. Oh well, a $50 lesson
A-Body glass install/adjust from FSM:
http://www.mediafire.com/?gszqbhz018ecb6r