So when your done finding out "how" to fireform a case, with by the way, from a wildcat that is on the extreme end of of the parent case as far as headspace, are you going to ask about loading data for a cartridge that, from the begining ran the gamut from hot to excessivley dangerous?
Fireforming cases is not difficult at all, but you need to tread lightly, and not take any advise lightly. There are alot of ways to get to the end result. yooper77 has given you 2 methods, In my "experience" one good and one not so good. You will have to decide what works for you. By the way, I have had complete case separation with one of the methods, which doesn't mean it won't work for you, just didn't in my case. (no pun intended). FYI, Rocky Gibbs and the wildcatters of the day, used a hydraulic case forming die mfg.ed by RCBS for his 30 Gibbs. Don't expect to find one in the catalog.
As far as loading data, I have pressure tested, loading data for the 30 gibbs and 30/06AI. In my world, there is not much velocity increase over the parent case, and no, that does not mean you should not persue your dreams. But when you finally get around to asking for any "real experiences out there" understand that a 300 win mag it will never be, and not even be close. Although I'm sure some have gotten 300 Pegasus velocities with there 22" barrels. If this is your 1st wildcat?, you picked a fine one for sure. Just don't get tunnel visioned into thinking its something it's not.
Good luck on your quest, alot of us have made the trip. CRASH87