I was looking at the firing order and distributor rotor direction on the diagrams Paul posted on a previous thread. The rotor rotation is clockwise which means the cam is turning the standard or left hand direction, which means the engine uses a timing gear on gear setup, no chain. The crank is turning CW, reverse rotaton. The cam is turning CCW therefore the distributor rotor is turning CW, as normal. The firing order is changed at the distributor by reversing the plug wires. The cam is ground to follow the reverse firing order.
I know this is confusing as heck!
Bottom line, this cam is not hard to find. Tell your parts supplier it uses a gear on gear cam drive. A Mercruiser 350 cubic inch/260 HP reverse/right hand engine uses this cam.