ubb.classic 6.7.3 is still available in the members area here, you could upgrade the 6.0.5 to that and import into ubb.threads then.
Otherwise, if your portable webserver runs some relatively recent version of perl then you should be able to run 6.0.5 fine on it. I would think there's security holes in it tho, I'd update soon if the public would have access to it.
