DR 750 crashbars are from Hessler. Ricky Cross. They are what he recommends as "best" but I took me 2 days to mod the mounting system so it didin't stick out so far that the front tire would contact is on full fork compression.
I've seen other pics of some of the other types with large pieces of flat stock that do not hold up at all in a tip-over.
My screen is a Givi. No longer made and rare as hens teen. Keep trying to find another with no luck. I think I may take it to a fiberglass master that I know and use it for a mold to make copies. Too low to look through even on the trail so an opaque finish would be OK.
Stefans pretty much the only game in town for DR Big modded bits.
Resi on the DR750 site has some nice stuff that he's built here:
http://www.bollertante.de/photo.html