A staggered setup will create understeer, which will make the car handle worse. A square setup is better for handling. Offset is really important. And, you will have less room on a 94-98 car, because the fenders are narrower than a New Edge. Your coil overs will also limit tire size a little (or require a spacer). And, negative camber will help the tires clear the fenders.
I do know people who have run 18x10" square rims with coil overs on 94-98 cars with 275/35/18 tires. But, every car is different, so they might not work on yours.
These videos might help.
The first one covers choosing the right size tires for autocross, but there's a lot of info in it that pertains to your question.
The second video covers the process I used to fit 315s on 18x10" SVE s350 rims on the front of my New Edge Mustang. With coil overs on a 94-98 Mustang, you probably won't be able to fit 315s on your car, but the process will show how you can test the rims and tires you want to use on your car.
A +20 offset seems to be the magic number for fitting 18x9.5" or 18x10" rims on these cars. If you have any questions, please ask.
