I was wondering about reverse rotation as well, got an oddball project in mind of bolting two weedies together back to back of the the three bolt round backplate of the McCulloch 25cc engines, as of yet its still undecided on the crankshaft coupling, could just be on ground flat the other slotted with a sleeve over everything.
Then I use a two cylinder spark box and after making sure both are at TDC use the timing from the front engine to spark both, OTOH maybe both would balance better if one was TDC and the other BDC. Yhe rear engine gets spark on BDC, OR...split the spark wire into a "Y". And unless I buy the CH kit I'm going to use an old 9volt powered hand taser for the high voltage rquirement, its small and lite and see if my electronics will come up with a hall switch or something, would be a project just to see if its possible to make an inline weedie conversion