To run a conventional two stroke glow front rotor engine in reverse rotation for a counter rotating twin engine airplane You would need either a reverse rotation crankshaft which you are unlikely to find or if the engine is an older two piece crankcase design with a four bolt removable front case and carburator. If it is this type then rotating the housing 180 degrees I think it is will allow reverse running.

You will still need a pusher prop on one engine mounted backward with the blade face toward the engine rather than facing away from the engine in a pusher installation. This severely limits your selection of props and the whole CR thing is grossly overrated and won't save your bacon if choose the wrong response when an engine does quit on you. The small advantage of not having a 'critical engine' with CR is simply not worth the considerable hassel.

John