Like the guys say,I think you're on your own regarding patch panels,cutting them from a junk cab is by far your best option,that way you know the contours should at least be close.

This is the first time i've seen someone wanting to go from 5 to 3 windows! grin

1950 Chevy Advance Design 3100 in Scotland
In the Stovebolt Gallery
More pix on Flickr.
I've definately got this truck thing in my blood ... my DNA sequence has torque settings
"Of all the small nations of this earth,perhaps only the ancient Greeks surpass the Scots in their contribution to mankind" Winston Churchill.