If you have a '95, you actually want the control arms so that you can upgrade to the newer style suspension that came out around late 1996 or so. See the kit at Genuine Saab for more info.
The 9-3 strut has a different top mount and will not bolt in to your NG900. You have to do a hybrid. It's not worth the trouble unless you are trying to use some particular spring that you can't get for an NG900.
I believe the hubs also changed in '97 to accommodate the brake upgrade. I don't think you can use them without changing your caliper carriers, rotors, etc, but someone else may know better.
Check the kit at GS, that should guide you to what you need for the upgrade. I think it's the control arms and stanchion arms, but look there. You might need the sway bar as it attaches differently, but I don't recall seeing it in the kit.
If you're doing all this work, you might want to install poly bushings. About the only thing that can wear in those parts is the bushings. I haven't heard of a ball joint wearing out... it's always the hydraulic bushings that go. Maybe put new boots on them.
I'd think about upgraded strut cartridges while you have it all out as the ones you get will likely be worn... and you can bump the handling at the same time. Springs if you want to go a little lower and bump the handling some more. Of course these items will add some cost.