Yes, you get the wheel/tire combination, set it up under the car where it fits, take the wheel to wheel measurements and build the rear to the wheels. Pay attention to pinion offset. Use the deepest wheel offset you can. The rear will be narrower (lighter), axles shorter, and the wheel will come off and on easier.

Narrowing the rear usually involves new axles. Great time to upgrade housing ends, bearings, axle size, etc. to the good stuff.

Car should be weighed to get the right spring the first time, but 110-120 is probably what you will end up with.