I have turbo'd and un-turbo'd my truck a couple times. Not to hard to put it back together. The main difference is that you'll want to keep you stock y-pipe and 1st cat in one piece rather than sawing it in half to weld to the downpipe. You'll just have to get an exhaust shop to fabricate the first cat section (or buy a spare 50-state magnaflow y-pipe to saw in half).Completely doable. Now that I have done it I could probably pull it all off in a couple of hours. I would suggest buying a set of manifolds, with downpipe and cat as that's the only part that's hard.
That said, this thing is supposed to be CARB compliant soon. I don't see any reason it wouldn't pass smog then. Thus, you could pass smog now stock and then bolt on the kit - you'd have 2 years for Joey to get the certificate.
Hopefully you'll just get the CARB cert and not have to worry about it.