356A Ground System
 

Working on a friends 356A and not sure what the grounding system is. I seem to remember that the older Porsches had a positive ground. Right or wrong? The battery is currently wired with a ground on the negative terminal.

Negative ground is correct.

Ditto, negative ground. Main ground is negative battery terminal to floor in frunk.

If you are doing any serious electrical work on the car, a MUST HAVE book is Joe Leoni's 356A-specific electrical book, available here: http://blocks-books.com/BLOCKS-BOOKS/356_Electrics.html

It has color-coded schematics, descriptions, trouble shooting tips down to every little wire and connection in the car.

Thanks, now my next question.
 

I rebuilt the fuel pump a couple of years ago after the car was in storage for some time. This summer I found considerable gas in the oil. Assumed the diaphragm had failed and allow the tank to drain into the engine even though the weep hole was open on the pump. The fuel pump looked OK but I redid it. How would gas enter the engine other than the pump? Also, what fuel stabilizer is recommended for a car that sits way more than it is driven?

Carbs?

You'll like find a lot more advice over at the 356 Registry board. http://porsche356registry.org/

If the carb floats were stuck, is the fuel tank high enough to allow the flow of gas through the pump and into the cylinders? I think you are on the right track. I will advise my friend to turn the fuel off in storage.

Probably not (after sitting it takes some time to get my 356's fuel to the rear). No expert here though.

The fuel tank is above the level of the floats (especially when full or 3/4)and will create pressure at the full cutoff valves on each float. If they are not sealing properly fuel will get into the intakes and eventually the oil. Although the gas will evaporate from the oil when run, I would change. Also replace the seats on the float valves. If the float valves are working the fuel in the float chamber will evaporate and this will cause hard starting. I run an electric fuel pump that is only used to fill the float chamber when sitting for awhile. Regardless it is a good practice to turn off the fuel at the tank petcock. Most folks run Stabil.