Hi Folks, been a lurker and glacial pace restorer of a CB550F2, having got bored waiting for a gasket kit for the 550 to come back into stock I did the logical thing

and on impulse bought a recently imported '72 CB350K4 in gentle maroon, in theory having only done 2800 miles (I have my doubts on that point!) . I plan to get it basically commissioned, run it for a while and do a full restore later. Whilst the bike is on original tyres and the engine cases not badly mullered its probably been harvested for parts (side panels, mirrors, tank cap etcall gone walkies). I've hit my first snag with a part made from unobtanium, its described as "tube cleaner joint" part 17213286000 (part 2 on this
https://www.cmsnl.com/honda-cb350k4-england_model16400/partslist/F12.html . All the usual sources in Europe are out, the only lead I found is a guy on ebay in the US who makes his own from urethane, with shipping etc it would work out at about £45 I reckon. I know this biz is expensive but £45 for a little bit of rubber!
Any out there going for a reasonable price, or perhaps any wisdom on workarounds so I can get the bike on the road asap? Any gurus out there can tell me how critical it is to have this in place, I am wondering if I can fashion a bit of pipe just to get the bike running?
Thanks!