If you got two Xbox's, or a friend who's close by that you truly trust, you could go on over to his house, recover the OG on the other Xbox, whilst keeping the main on yours. Once you get to this point, have both controllers next to you. Change the Gamertag on the OG to something, while having that very same Gamertag ready to be changed on the main. Once changed from the OG, the tag should be available. I have done this before for a friend who bought a tag from me in real life. We would game together at his house, and I had a semi he wanted so he bought points for both the accounts, was ready to change his tag to the one I gave him, while I changed it off my console..
I will list what I am talking about in steps:
1.) Have two Xbox 's at the ready.
2.) Recover either one or the other accounts onto each of the consoles. (If you want the Main to have less consoles on it, I suggest recovering the OG on the console you will not use.)
3.) Have $10.00 readily available on both accounts so they are ready for the swap.
4.) Set both accounts up at the "Change Your Gamertag" screen.
5.) On the Main account, type in the space what your OG would be. As for the OG account, you would type whatever is available.
6.) To do this properly, Have both controllers at your fingers. Quickly change the OG to whatever you type in that is available. Once you get the notification that it was successfully changed, immediately change the Gamertag on the Main to what your OG was.
I hope this helped you out BasedGod. Let me know what you think. I have done this multiple times, so I can tell you this works.