Just FYI - to share some of my findings...
Wilbers still sell shocks for big DRs. Not the cheapest, but not too expensive either for all adjustable shocks. I got Wilbers on my sportbike and they are brilliant piece of kit. As for the front - perhaps not really big step, but front from DR800 SR43 series is 43 mm forks (thou not cartridge type) and front wheel with 300 mm brake disk and work suprisingly good. Can be bought off eBay in Germany really cheap. Then Africa Twin front fits too. One of guys I was in contact with put some beefy KTM WP USD front on his DR, but I think this is wrong approach - I saw way too many upgrades to superbeefy forks ending up with simple accident resulting in torn headstock. Because frame was not designed to hold that much force in impact and supebeefy forks = frame fails before forks bend.
Also, I been told that KLX650 front is almost bolt-on for big DR, but for which one (750 or SR43 800 or SR43 800) I do not know.