I've got SN95 spindles/PBR calipers, and rotors on my 79 Fairmont. I think I'm going to have to upgrade the MC on the car to really take advantage of the larger brakes, but I can hopefully at least give you some pointers.
1) The SN spindles have narrower strut mounting bosses than the 79 pieces, so they're not a direct bolt in. You need to get a spacer made (around .1" thick x 4" long with appropriate hole spacing).
2) SN brakes utilize a separate rotor and hub assembly rather than the integral rotor/hub assembly of the Fairmont units.
3) You're going to have a challenge on your hands to get your 15x3.5 skinny wheels to clear the caliper mounts without getting the cast "bar" that ties the front of the mount to the rear. It needs to be thinned to about 1/3 it's original thickness. What I ended up doing was getting some 15x5 wheels with 1.5" rear spacing, which pulled the outer sidewall of the tires inboard about 5/8", otherwise you're tightrope walking between having sufficient wheel/caliper clearance and rubbing on the inner edge of the front fender opening. Oh, you also should plan to run at least a 1/4" spacer to space the wheels outboard to ensure safe wheel/caliper clearances.
There are differences between the 94-95 spindles and the 96-up pieces re steering arm inclination and inboard/outboard position.
It ain't a straight forward swap. I can vouch for that.
Here's a URL that will provide some more info for you...
http://svo73mm.cjb.net/ There's a 94-01 V6/GT Upgrade link that you'll need to use.
Also, here's a URL for a pic of what my car looks like with the 15x5 wheels:
Hope this all helps (or at least answers some of your questions) in some way.