I subscribed to Vintage Vans a few years ago...still a member, but it is very quiet there as far as restoration goes. More of a place to announce the latest offerings for sale online from ebag and Craigslip.
The A-100 pickup with a slant & auto, has a big block 727 in it. There is an adapter plate to fit the slant to the trans. I was a member of an A-100 club in MD and they had the info on putting the B engine into an A-100 using mostly stock parts. I have lost my copy of it, and don't know if they are still around.