I'd be very inclined to pull the axles and have the long studs pressed out of the axle hubs and go back in with std ones.
These studs thread in and have a retaning nut on the back of them. No pressing required. Unfortunatly, the are a 5/8 thread in the axle, which most manufacturers carryover to 5/8 shank with 5/8 lugs. Instead of a traditional mag lug nut that threads the whole shoulder in to the wheel, these have a stud big enough to replace the shouldered lug.
Depending on who made the axles, they may have thread in 1/2 studs, but I doubt it. You might have to make your own with some 5/8 threaded stock which you turn down and rethread to 1/2 outside of the axle flange engagement area. Otherwise, you may need to replace the axles, and depending on the spline count on the carrier engagement, maybe even the ring gear carrier.
A lot of work to put heavier wheels on your car.