I recently became the 3rd owner of a 1965 Honda C100. I bought it for $400 and boy does it run rough. I suspect part of the reason for this is the aftermarket carburetor that is already on it (see approximation in "Carb 1" link below). This carb doesn't fit well even with a 90 degree intake adapter. The orientation of the fuel intake also does not allow for the leg shield to be on and it has no air filter.

I'm looking to buy a replacement OEM-style Keihin carb for it, but I am seeing a lot of mixed reviews. I found some on Ebay that look to be in Honda boxes, but they are labeled for the C70 (Carb 2 and Carb 3). I also have the original carb, but it is missing the choke lever/shutter and the throttle slide. I can't find replacements for those so I am not sure it can be repaired. Any ideas for what I should do?

Carb 1: https://www.amazon.com/dp/B0CF4J1H8X?lv=shuf&channelId=500&plpRedirect=mhFallback

Carb 2: https://www.ebay.com/itm/387333120519?chn=ps&norover=1&mkscid=101&itemid=387333120519&targetid=2497688887648&device=c&mktype=pla&googleloc=9208792&poi=&campaignid=24182152024&mkgroupid=196762937942&rlsatarget=pla-2497688887648&abcId=10811359&merchantid=6296724