I'm currently using the iPhone 3Gs on 3.1.2 firmware, it has been jailbroken using blackra1n.

I'm wonder what the best possible way it is to upgrade to 3.1.3? Because i prefer the untethereed jailbreak. I've been reading and tried and it says i cannot restore back to 3.1.2 because "This device isnt eligible..." i understand why, apple wont sign something

So now im wondering how i would upgeade? Would it be ok to download 3.1.3 and SHIFT+resotre it?

PS. My SHSH blobs are saved with cydia