Restore loop: used spirit after blackra1n 3.1.2 - cannot restore :(

[sRyan]

Like an idiot, I was successfully running my 3GS on 3.1.2 using tethered jailbreak from blackra1n and decided I would try the untethered jailbreak by spirit, so I ran it not knowing this would throw it into a recovery loop.

Details:

Using macbook pro (also windows xp via parallels, but has limited usage)
iPhone 3GS new bootrom
BB 05.11.07 - was jailbroken and unlocked
I do NOT have shsh's for 3.1.2 or any firmware
iTunes 10.4 (current)
Edited host file to point to Saurik's signing server

I am able to put the device in either DFU mode or Recovery mode and iTunes does recognize it.

I have done over 20 hours of reading online to no avail. I've attempted step by step tutorials that apparently work for some, but the big setback is that iTunes is refusing any and all IPSW files I throw at it.

Since I don't have the shsh file, I believe the only firmware Apple is currently signing is 4.3.4. This would update the baseband and make it impossible to unlock, right? I'm afraid to let iTunes automatically download and restore the current firmware since the device was jailbroken and unlocked previously.

I really appreciate any help.