clean, repair reseal your carb if at all possible. All the aftermarket carbs are the same weather $20 or 65 they are all mokuni knockoffs. The real mikuni carbs are a lot better so as long as your shafts aren't all slopped out you should be good. Ive heard of people using briggs and Stratton fuel pumps with good luck but i have no idea what pump exactly.
i could post parts manuals here also but i use this site. Note this site is over seas so shipping would be expensive, but there parts break downs are top notch and they still list discontinued part numbers which helps when surfing ebay.
https://www.cmsnl.com/yamaha-g1_model16648/
when searching parts always add the dashes. after the first three and before the last 2. example. cmsn lists 10V1361001. But yamaha labels the part like so 10V-13610-01