If all else fails, get a book on the subject. Here is what I would call an excellent source of info on OS engines.

If you look at the picture of the timing marks it says to set at the 6 0'clock position. HOWEVER, you will also notice that the mark and the center of the camshaft align with the pushrods. When the engine is positioned as it would be in a mount with the crankshaft horizontal, The marks don't align in the 6 o'clock position. The pushrods are canted backwards a few degrees. It's all a matter of symantics. Ignore the statements about clock positions and align the mark, center of camshaft, and pushrods and the timing will be right on.

I've been timing OS and the clones this way for years and it is perfect.