Van seats in an early A?
I have swaped various seats into various cars. As long as the seat tracks fit inbetween the frame rail and tranny hump, your mostly good to go with the tight drill bit and hardware.
In my Duster, I swung in 2001 Concord seat. The draw back is they do not lean foward. Comfy though. I had to fab up some simple brackets out of box beam. Click below.
http://www.forabodiesonly.com/mopar/showthread.php?t=10508&page=8