Update: My right side carb manifold was damaged but thankfully I was able to find another. Regarding the O ring/gasket issue so far I have discovered that there is no gasket, ……O ring ONLY. That makes sense because the O ring is only 2mm thick so a gasket would negate the O ring space and ability to seal. The boots mate to the cylinder head surface, with the O ring providing sealing to an almost metal (cylinder head) to metal (metal flange on carb boot) surfaces. My right side carb boot O ring was flattened out and harder than the other. Probably because of the small air leak (from the damaged boot), made that cylinder run leaner, hotter. Both O rings on the carbs were nitrile, aka buna-n. That material has a heat limit below the potential cylinder temps. I was able to finally find O rings made of “Viton”, which has a heat range within the cylinder head temps. I haven’t got the bike running yet but will let others know how well my carbs work after I rebuild them. Thanks for other forum members for their help along the way to restoring this old bike.