Welcome to the site. Often times bikes were made the year prior, in Japan, so it would be ready to selling the following year. The vin sticker may say 1972, but that is the manufacturer date (not the model year). The model is a 1973 GT1.

The rubber elbow is still available directly from Yamaha the part number is 367-14453-02-00

Original carb's are rare, but that would be my first choice. If you go aftermarket...I would buy a genuine Mikuni over a Chinese Knock off.