302, I like those rims! Look great on the car.
I also like the drag lites, as I believe they are called, but expensive....I think.
I also like the American Racing Torque Thrust series wheels, but not sure if they fit your car.
What look are you going for? Chrome? Throw Back? Modern? Painted?
Here is a nice 4 lug wheel:
http://www.wheelreplicas.com/cobrar4lug.htm
In silver it's only $499 a set for 16 inchers.
Here is another:
http://www.afswheels.com/v2/ecommerce/shopexd.asp?id=3
Look at the prices and cut them in about half. That is what they sell for on ebay from this company.
This is an awsome website for wheels if you want to have some fun. Tons of vintage stuff:
http://www.wheelvintiques.com/
Look at these gallery photos. Check out the Magnum Wheels on the Mustangs. You will need to scroll down and hopefully this link below will take you to the right place. The dark grey '03 Mach 1 is the personal car of one of the staff (Advertising Manager) at MM&FF. That is how I learned about these wheels. Some of the nicest wheels I have ever seen on a Mustang. Not sure if they would work on your car, though.
http://www.wheelvintiques.com/billetgallery.html
Looking for wheels is one of the most fun things you can do.
I just purchased these for my car (black "deep dish bullets):
http://www.crossroadzdirect.com/