Increase the vent size to 4" and change the single wall wye to double wall. Replace the gate valve with a quarter turn shut off, both flex connectors, change the gas ball valve to a hand turn 1/4 turn shut off and a flex connector. If it's on wood floor or a finished basement put it in a pan and pipe it to the drain. Oh yeah and make sure it has a t&p pipe no more than 6" from the ground.

Pull a permit. Yah yah I know govt takes too much this and that, it's $40 or less and piece of mind if you have to go head to head with the insurance company.

Easy peasy.