Advice Please - Considering Submariner circa 1970

I'll echo Larry's advice and add the following. Just my personal opinion and past experience.
Vintage Rolex sports models are a snake pit. The eye popping prices asked for overpolished and unserviced (2 out of 3 in your links) demand a huge leap of faith. Since Rolex will most likely not service these watches, daily wear becomes an issue and forget about collector grade in all three of those examples. Train your eyes on great cases and learn how to recognize relumed and cooked dials. Get a serviced watch for which you know genuine Rolex parts were used.
The references you're looking at were made in large numbers so be patient a look for the right example.

Edit: I should have added to be aware of the proliferation of laser welded cases. When you see that perfect case in a 50 year old watch?! The problem lies when the seller claims "unpolished". If a such a case is disclosed, then, so be it. Depending on the price, a refurbished case can do the trick for certain enthusiasts. Just don't get fooled.