Just dump the keys and spoof it to a stock firmware.
Flash the drive and put it back in the 360, update it and then take the drive out, spoof your keys to LT+ 3.0 and flash that to the drive.
This makes a lot of sense.
However, since I would be flashing stock firmware, wouldn't I lose the ability to reflash it afterwards?
Oh, or do you mean I should *spoof* to stock, not actually flash stock, right?
Would I still have the "back door" to flash it without additional hardware?