The only difference you need to be concerned about is the crank (you would not use the cam). The opposite rotation cranks have the groves that move
oil away from the rear main going in the opposite direction. They need to be polished off to a smooth surface. I have used both cranks without any problems.
In most cases the marine blocks are a good choice. Most have never been bored and have plenty of deck height.
You can even have them drilled and converted into a true side oiler if you want.
Standing in front of the engine the standard rotation goes clockwise.
You can always build a stroker and not use the 427 crank.