Safe to Restore to 4.0.1 stock IPSW?
I just got ahold of an unlockable 3gs with 4.0.1 from a friend. I was able to jailbreak with jailbreakme and unlock with UltraSn0w.
Currently it has all of my friends contacts/photos/apps on it and I'd like to restore and load up the backup of my now defunct 3g phone's info from an iTunes sync backup to get back my information.
I have downloaded the 4.0.1 ipsw from apple. Now my question is, is it safe to restore the phone in iTunes (Win/10.0.0.68) by holding down shift and selecting the downloaded stock 4.0.1 ipsw? Most importantly will it maintain the unlockable 05.13.04 baseband?
Is there anything I have to be aware of as far as:
3) ultrasn0w unlock?
Also, let me know if there is a preferred method (possibly using Sn0wbreeze?) to restore to any of the i0S 4.x while maintaining my baseband and ability to unlock.
Thanks so much in advance!