Upsizing Gas Line From Tee
Since you have a union right there changing the T should not be that tough. There is a nipple to the right if lengths change. I might try the existing But any time another appliance with no restrictions turns on the new one may starve for fuel. I have seen your plan work but since doing it right would not be much more work and possibly only changing the T, I would do that so I would not have to go back and do it over with all the new pipe in place needing to be removed to upgrade the T if it doesn’t work.