Most likely no. With the xt907's, if you do manage to go back you find that you didn't flash the old bootloader. So it's still not hackable. Currently it is possible to unlock the bootloader on xt907's by UPgrading to the new KitKat release, rooting with towelroot and then you can use the old bootloader hack to unlock.
So your question now turns into, "can you RSD a 907 image onto a 905?" I don't know or have a 905 so I'll let you do the searches. I'd guess flashing the radio from a 907 could lead to a brick, but maybe you only flash part. The signing keys might be different so you'll be hosed.
If you can flash the whole thing, you're gold.
If you can flash everything but the radio, and KitKat will boot with the old radio, (even if you won't get a signal) then do that. I bet nobody knows the answer to this yet. KK might not work, or the new bootloader will think the radio image is unsigned and croak. At this point you're probably bricked until the 905's get KK because you can't downgrade the bootloader.
If KK won't boot with the old radio, will the new bootloader accept the signing keys from the old stuff? Probably not, but if it did, you can replace only the bootloader and then unlock.
BTW: stock images for xt905: http://sbf.droid-developers.org/phone.php?device=20
---------- Post added at 01:25 PM ---------- Previous post was at 12:56 PM ----------
Sounds like you're out of luck see http://forum.xda-developers.com/show...9&postcount=22