Bruce,
Your engine being inverted is an important factor which makes your needle settings more critical. An inverted engine is much more likely to die from a too rich mixture quencing the glow plug. Starts on an inverted engine are often more difficult since it is much easier to overprime (flood) an engine and quench the glowing glow plug.

Right now replace that Non-OS plug and put an OS 8 or OS 3. Both are pretty hot plugs and work great.

If rpm drops a great deal when a glow driver is removed it can mean that the plug is too cold or the mixture is too rich. If your engine dies when glow driver is removed, it probably means your mixture is too rich.

So, get your engine running again at whatever throttle setting works. If you get it running at 1/4 throttle that is fine. With engine running at 1/4 throttle pinch fuel line and hold until engine dies. If engine speeds up a bunch and takes longer than 2.5 seconds to die than than the needle valve (low end in this case) is too rich. Make very small adjustments. You may have to start and stop the engine 4-10 times to get it dialed in right. Patience is extremely important. With each attempt at same throttle setting, 1/4 throttle in your case, remove the glow plug. If it keeps dying and pinch test verifies that it si too rich by taking longer than 2.5 seconds to die with pinch and held then adjust again. Once you can get it to run without a glow driver you are now much closer to getting that puppy out to the field.

Ok, we now assume you got the engine to idle at 1/4 throttle without a glow driver attached. Now slowly transition to full throttle. Have someone hold or tie the airplane down during this step. With transmitter in one hand, as you advance throttle keep listening to what your engine is telling you. If the engine stumbles and spits out a lot of fuel but is still running then you are too rich on high end (when above 1/2 throttle this needle valve is the one that is adjusted). To verify mixture is too rich, as your are transitioning, don't be afraid to pinch and release the fuel tubing. In some cases you can keep an engine that is too rich from dying by manually controlling (leaning) the fuel mixture with repetitive pinching/releasing until you can get to the high end mixture needle and close her about an 1/8 turn at a time.

Eventually you will get to full throttle from your start idle 1/4 throttle setting. Once at full throttle let her warm up for about 15 seconds before you do anything. After 15 seconds or so, pinch fuel tubing and release (hold until engine just appears to be dropping off from fuel starvation, about 1/2 second). If engine speeds up too much, lean out a little bit at a time. If engine doesn't speed up at all, richen a little. Once high end needle is set, return to your 1/4 throttle setting and check your transition from low to high. If the transition is a little rouch and stumbles but doesn't die, don't worry. Your engine is still new and you should focus on setting the idle and transition only after you've got at least 45 minutes of run time on the engine.

To break in the engine, run at full throttle about 400-500 rpm shy of max lean rpm (if your engine runs without glow and it speeds up a bunch when pinches, this is fine) A little richer than normal is ideal for breakin. The process I gave you above for setting your needle setting is more for flying after engine has been broken in. You should run her slightly rich but not so rich that she is 4 stroking and needs glow power. Run engine for 2 minutes 1st time at full throttle. Let cool completely, start and run for 4 minutes next time (each time ensuring with pinch test you are not too lean or too rich). Repeat after each cooldown doubling the time run. After 30-45 minutes you can now focus on the low end mixture. This is an art and has a lot to do with listening to what your engine is telling you.

The best way to fine tune your low end is as follows. Start engine, run to full throttle, let warmup and set high end needle 400 rpm shy of max lean (verify with pinch test). After engine is warmed up, go to idle and snap throttle to full throttle. If engine stumbles and burps and spits out fuel, the low end is too rich. Make very small adjustments. Low end is set when engine snaps to full throttle and can run about 1 minute at idle without loading up. Loading up occurs when a too rich low end needle valve mixture allows too much fuel to pool up in the crankcrase. At idle an engine may not have enough vacumn to suck all of that fuel. When you transition to full throttle it gets sucked in by the engine vacumn and causes your engine to stumble, smoke, and occasionaly quency the glow plug. If low end is inadvertently set too lean, engine will just outright quit at idle or when you snap the throttle to full throttle. Its that simple. It just takes patience and SMALL adjustments.

After you have set your low end, double check your high end. The low end can affect the high end setting but usually not vice versa. Once the low end is set the only setting you will ever have to touch is the high end (unless you switch fuels or move to a higher altitude).

Good luck and please let me know how it goes.

Glood luck,
Andy