You do need nitro for serving through a nitro (stout) faucet, but you don't need either to serve a stout. If you want to serve on nitro, I'd take the spare tank to the local welding supply shop and swap it for a tank of beer gas, and sell the spare CO2 reg. Then you'd need to buy a nitro reg and nitro faucet, and you'd be set.
I'm trying to find some porn filmed by a dog wearing a GoPro. - SharonaZamboni