Or you could use the straight axle out of a a-100 van and leave the k-frame in the stock location.
There is a very good article written by Steve Magnante on a 64 Dart he made into an altered wheelbase car. It is the same procedure to alter the wheel base on a 64 b-body.
64 Altered wheelbase Dart Article Here are a bunch of pictures they took when they built the car.
64 Altered Dart PicsHe and a friend Dale Snoke started a company called The Funny Car Farm in Pomona, CA
http://www.thefunnycarfarm.com/ They make and sell a DVD on doing altered wheelbase conversions it costs like $10-$15 bucks, lots of good information on it.
The Funny Car Farm is also building a 64 Polara altered wheelbase car.
Here are some photos of their progress.
64 Polara AWB Also Mopars by Mosher website has some info
http://www.moparsbymosher.com/ and SS and AFX, Inc.
http://www.ssandafx.com/ has some info and products like seat tracks, delete plates, etc.
Also Jim Kramer
http://www.kramerauto.com/ sells a lot of parts used on the altered wheelbase cars, like seat tracks, hood scoops, delete plates, etc...
Here is a good website with a 65 Belvedere AWB build up.
http://afxer.com/documents/29.html