Oil weight always has confused me. I can't make a good recommendation on that one. It depends upon the type of weather and temperature outside. Tom has used Mobil 1 Synthetic in all his cars because he has seen the actual valves in his car turn from light brown back to 'newish' looking after running the synthetic oil for a while.

I personally don't run synthetic very often in my cars, because they have been apart so much lately, that replacing the oil so often would bankrupt me. But normally, I would recommend the synthetic.

As for the gas type, I would run only high octane fuel in the car. These cars were designed for different fuels than are available today. I could go into a long explanation of why, but this is already answered on our site:

http://www.pelicanparts.com/914/914QA/914Q_engine_fuel_octane.htm

I think that this will answer your question.

Any other opinions?

Back in my 2.0 liter days I ran either 20W50 or 10W40, depending on the weather. My car ran really hot, so the 20W50 worked well in warm weather.
I didn't have good luck with synthetic, though. Synth is sliprier (some even say less viscosity) than regular oil, and it made my motor leak a lot. When I switched back to regular oil, the leaks subsided.
If your motor has good seals it probably wouldn't be an issue.
As far as fuel goes, higher octane is better.