He replaced the stock carb with a Walbro WT759 which is discontinued and might be difficult to find, but a WT739 will do just as well.

A quote from Jody, "If one must have a Walbro there are many that will work well, all are 28-34/64" venturis, ones I've tried that work good are 739, 759, 645, and 805."

Karol