Quoted:
So, I'll preface this with, I'm a writer, not professionally but something i do in my free time.
I like to get details right, so, for the purposes of my narrative...
What would happen if, in a DC-3 (twin-wasp engined)
1) you ran an engine on only one magneto.
2) you immediately went to rated power after a cold start.
for the purposes of the questions (and the story) it's not a completely worn the fuck out plane, but it's not not running freshly rebuilt engines either.
1) Engine should run smooth but not develop full rated power.
2) It would do it but it would do damage to the engine because of lack of proper lubrication. Normally you would wait for a minimum of 40 degrees C before exceeding 1000 RPM. You might also rupture an oil cooler.
Running max power on one engine and then stalling the airplane would result in a VMC roll over and from 800 feet in a DC-3 you would not be able to recover before making a crater.
I got my ATP in a 1937 model DC-3, year of our Lord 1974. We have the Continental DC-3 at Lone Star Flight Museum.