I have heard that the Bilsteins have issues above a certain spring rate.... not confirmed though. I run the Koni's and have been pleased. Boge is a type of shock manufacturer/housing design - I believe this one is the kind that you screw into place and hold it in with a captive nut as opposed to bolting them in from the bottom of the strut tower.
I believe the early cars had the Boge type of shocks but dont quote me. They are not adjustable without modification to the strut tower itself. Try here for 944 Spec suspension: (about 3/4 of the way down the page)
www.paragon-products.com/SearchResults.asp
The year of your car determines what pakage you run (i.e. Koni package 1,2,3, or 4) They have put a package together with everything you need and they will do the conversion for you if you ship them your strut towers (uncompressed). That way you can just bolt the new ones right in and they are adjustable. If you want to call them, ask for Jason he is the man and is very helpful.