360 Running Issue(s)?

Today we took the vehicle's entire fuel system completely out of the equation. We put a small electric pump from a gas can directly to the carburetor. Fired it up and it ran for 10-12 minutes then did the "sputter/fart/die" scenario AGAIN. I believe we can now eliminate the fuel system from the equation.
When the engine is in the "sputter/fart/die" situation the tach needle is bouncing quickly and erratically, and all other gauges read normally (including ammeter). The ammeter leads have not been shorted together (bypassing the ammeter) as of yet. That is still on his list of things "to do".
Any other advice or direction?