I can expand a little on vern. Mostly what will need to be done.
First, longer forks are needed BUT if you want to keep the frame geometry correct, you will need to cut off the neck tube and reangle it to allow more rake then weld it back on.
For the swingarm, you can make a custom one. There was a person here who stretched his out. Check in the members bikes or build areas. You could also get one made by swingarms.com but it is expensive.
From there, the seat will need to be fabbed or you will need to mod a single seat from a harley.
do a search on konging. If you are already going to cut up the frame, you may as well do that and lower the seat while keeping the suspension.
Best I got for ya. woodsrider250 or polymer might be able to give you more info.
The ride IS the adventure. The destination is just to get gas!