Nice seeing you back in the game, GA.

Not too sure I'd trust success to that technique, but I've never tried. Since it's the last of this strain, I'd prefer to see ya re-veg and take clones, or cut one branch off and re-root it...leaving the rootball on the other branch. This would minimize the damage and increase the odds of at least one of them surviving rather than losing both halves. If you do this though, immediatelly drop the injuries in water to keep from having air suck-up into the cuts. (a death sentance)

If you do cut one branch of the "Y" off, leave an inch or so on the other half with roots. Otherwise, you risk the "Y" dying-off.

Once you split at the "Y" there will be a huge chunk of trunk missing from each half. (from the "Y" to the soil) This is a major injury. The trunk has a couple of protective layers that protect the plant from disease, and exposure to air will dry-out the surrounding tissue. (but if you keep the injury moist, you risk mold or disease) Perhaps wrapping the injury with garden tape would help. (the green stretchy kind)

I'm not too sure if burying the injury would be a good idea either, as disease loves to crawl into any nook-n-cranny it can find. Might be able to coat the injury with a light coat of rooting compound and bury it, but I'm just guessing...