If on the rooted gb:
1: download either maderstock340 or the tbh monster340 zip to your sd card.
2: boot into recovery using d2 bootstrap app. (dx bootstrap doesn't work on gb)
3: install the zip from step one, reboot to stock 340
4: use z4root to reroot and the dx bootstrap to go into clockwork recovery.
5: restore your rubix backup or install any 340 based rom as usual.
I believe this is inaccurate, you have to sbf back to .340. You can't simply flash a zip back to stock. GB is a completely new system, it won't recognize .340 roms or files.
No, its correct. Maderstock is the zip equivalent of an sbf. Its already been tried and works.
sent from a D2G with Liberty 2
Not from rooted gb it won't, the op states, "If on the rooted gb:"