The OS should not give you any problems inverted. I have an OS 1.20 AX inverted on an Excelleron 90 pattern plane and it starts and runs just fine.

The engine quitting could be several issues. How far back is the tank from the engine? Did you have the mixture set right? Was it to lean or to rich (most likely to lean)? The pressure from the tank is something that you have to make sure about.. are you using the right tubing? Is the tubing on tight? It could have come off during flight, too. I've done that and never noticed it until it happened on the next flight. It got airborne, but it quit pretty quickly after that. It will draw on it's own but really needs pressure to maintain.

I've never needed a remote glow igniter and I have three OS 1.20's, and two OS .75 AX's (as well as other OS engines of different sizes). I also have a 1.60 but have not yet run that engine.

CGr