MMike: my 98 610 has a wheel base of 230 and the bed, built by Doonan in Wichita is 8' wide by 11' long.
I kept the rear axle where it was and built up another drive line with a carrier bearing. We carry two motorcycles behind the cab, a 750 Honda Shadow and a 650 "V" Star.
E-mail me at firstname.lastname@example.org
and I will send you my conversion process at Doonan's.
Go to the photo's on this site and take a look at my pictures.