I think you are referring to Mr. Gizmow from the TW200 site. I've chatted with him on a number of occasions. He has a number of novel ideas.
You're NX is a fantastic bike for you. Maybe not so good for when you get old and fat like the rest of us who need big CC engines to compensate for expanding waistlines and receding hairlines.
Your biggest triumph so far is getting that swingarm bolt out with no drama.
There are Chinese copies of the carb on ebay that cost a little bit more than an overhaul kit for the original. The moderator from the Yahoo group just tried one on his 200 and gave it a huge thumbs up.
I love the stock tires, but as you probably know, they are out of production and usually only found under a pile of hens' teeth. It comes down to personal preferences as far as what type of riding you are going to do. Mud? Snow? Supermoto? Freestyle? Your options are heavily limited by the 9" rim on the rear.