The main problem, in my opinion, with trying to run these in stock classes is the tires. Even with the 16" wheels, there's not much for tires, and there's just too much sidewall. I don't know what the classes for you are like, but here, we've got special street tire classes for stock cars on street tires, a class for non-stock cars (with the exception of the Street Touring) on street tires, and classes for cars on race tires. If your club(s)don't do that, and all FS cars run against each other, I'd really think about going to a Street Touring class, which allows, among other things, wheels up to 18x9. And a 18 inch wheel on these works great. The usual size most of us use on these, 245/45-18, is an available size for the Bridgestone Potenza RE-01R, which was the best tire a few years back, I can't remember off the top of my head if the new version, the RE-11, comes in the same size, but the RE-01R, even though discontinued, is available on eBay, in our sizes.
I'm still running the stock sway bars, and while they could be stiffer, they work fine. The more standard ones on your '94, however, probably would need to be upgraded to be really competitive, and I think in the ST classes, both can be changed.
As for brakes, I know for the factory 96-7 Sport cars, with the 16" factory wheels and bigger brakes, there are no real good pads available. Hawk doesn't show anything available for the big brake cars except for a stock replacement type. I doubt that there's anything available for the normal brake cars either. I don't remember if you can change calipers in stock class (I wasn't stock going in, so I didn't read too much into the stock rules), but if it's allowed, swapping to the PBR twin piston caliper from the '99-+ Mustang is supposed to be a good upgrade, and that would also open up to better pads, I'm sure the HPS+ is available for those. Search the forums here for more info on that swap.
Gear changes aren't allowed until the Street Modified class per the rules, so use your own discression. Consider that the '96-7 cars could have a 3.27 rear gear, and there were trac-loks available in those too.
I imagine one could swap some of the rear suspension parts for the MkVIII parts, but I'm not sure just how much weight there is to be saved.
3 year autocrosser
1997 T-Bird Sport, 'Interceptor' (12 ESP 2008-2012)- CAI, 2.25 duals, Flowmaster 40 series, Clear corners, BBK 70mm Throttle Body, TrickFlow upper intake, PI Intake, BBK adjustable fuel pressure regulator, LE stripes, Bullitt-style gauge faces. 18x9 wheels, Sniper tuned, 3,620 pounds
1991 Ford F250 - Air restrictor delete. Cat delete.
1991 T-Bird 'Interceptor II' (12 CP 2013-) - Race-prep, Full custom "interior", Carb'd 302, Trick Flow twisted wedge heads, stage 1 cam, Custom Koni coil-overs front, Koni yellows rear, Cobra front brakes, fuel cell, 18X9 wheels, 275/30 Hoosier A6, 4.11 T-Lok. 3000 pounds
2004 Toyota Solara SE - V6, Sport package, Muffler delete, 17X7 wheels, 235/50 Conti ExtremeContact DWS