Hi Raz,
I'm doing the same on my 49 P15C. The felt that goes inside the metal channel is one of the parts I haven't found, even on Mark's restoration videos on youtube dont match the ones for 46 thru 49. So, after trying a few different mopar ones from the 60's I found one that fits. You just have to cut it to length. CRL Flexible Flocked Rubber Glass Run Channel for 1960-1961 Valiant and Lancer - 96 in long - - Amazon.com
There is a guide on the top of the channel that I need and can't find either.
If your still in need of the info, I hope this helps.
Here are Marks video's