I’d find out what kind of konis they are. Ones for 900 retail aren’t super common, but the race konis are up there, and double adjustable are even more. As for the mopar high rate spings that “arent made anymore”, those aren’t a big deal because there are plenty of companies that will make you custom spings for you cheap (ground control). The diff, if you can use it may make this very worth it for you though.
Oh and to have your konis revalved, yeah it’ll be somewhere in that ballpark.