I started measuring different brands of USD forks to see if something would come close. The main issues were lack of right side caliper bracket on all the off road forks.
The next issue was all the modern internals are all bigger than the F8s.
The next issue is that the triples are too weak to go boring them out to accommodate larger forks.
The next issue is that any proper off road front end is about 10~13mm narrower from fork centre to fork centre across the triples.
You can start machining internals and stuff, but then you have to machine replacements when they wear out. I'd rather opt for an off the shelf deal.
I have the parts to fit a motocross front end, I just lost interest in the F800 along the way. It's actually frustrated me so much I went away for the long weekend in my car.
I'll see if I can get my bike mojo back and finish it. At the moment I can't be bothered riding it anywhere. Everytime I think of somewhere to ride it, I figure it'll only disappoint me. It'll pass.