So the answer is no to both of your questions, if you look at your camshaft the Distribitor gear is cast as par of the camshaft and the gear is machined with its teeth going in one direction. The Distribtor gear has to has to mesh into the camshaft gear a different gear isn't going to fit and mesh into the cam gear and they aren't made anyway. The engines crankshaft would need to turn in reverse to turn the distributor counter clockwise. And the camshaft would also have to be specially ground so the cam lobes open and closed the valves opposite of a stock 250 six for the engine would run in the oposite direction. Very few engines are made to operate this way one Application is for one engine used in a twin engine boat however I haven't heard of any of them using a pair of 250 Six'es in them. Next the starter motors electrical coils would need to be rewound in the oposite direction in order for the starter to turn and start the engine in tgat reverse direction. Then the transmission gears would also be turning in the wrong direction giving you as an example for a simple three speed trans, three reverse gears and only one forward gear and lastly the rear axel would be turning in the wrong direction to. As you can see it would be far to many things that would need to be custom made.
Did you happen to look at that above link? So again the real reason for your confusion is that you are standing at the front of the car facing the engine, the way automotive technical things have always been described on cars and trucks is from someone standing at the rear of the car facing toward the front or else also by when you are setting behind the steering wheel facing forward and still behind the engine. So remember that as soon as your standing in front of the car facing the engine then everthing is now in reseverse. Best of luck