The engine mount bolt (if it's the lower) is 12mm and you won't find a "bolt" that long. Some use threaded rod, cut to length. Others buy solid rod, a tap, and make their own. But as far as I know, I've never seen "longer" bolts made or available anywhere.
The swing arm bolt is even more difficult to locate, so making a replacement is needed, except if yours is grooved for grease, that's more complicated. Can you post a picture of which rear set brackets you bought, as Cognito sells a few different versions.
