Newb here, so someone chime in if my information is wrong, but if you don't mind spending more money than what would otherwise be reasonable (if we were living in reasonable times), what you need more than anything else right now is the p320 FCU (fire control unit). That's the serial numbered part that's covered under the rapidly approaching transfer suspension deadline. Grab any p320 you can find (like the "SIG SAUER P320 9MM 4.7BBL NITRON FULL SIZE" that is available from a couple of CGN vendors as of this writing). Once the bank account has recovered, purchase Sig's "P320 XFIVE TXG Caliber X-Change Kit", and optionally upgrade your trigger. Pop in the FCU from your donor pistol, and you've got essentially a DIY XFive Legion. One gun for the normal price of two (thanks Trudeau!), but you get what you want while you still can.