I have an LT 40 with an OS40LA (little underpowered) and it seems to want to die at idle constantly. I have had 3 very experienced guys at the field adjust the needle valve and the air bleed and it does not help. It is only turning 10,600 rpm at full throttle. I have an MAS 11X5 prop on it. I have many possible solutions out there:

1. Go to a 10X5-6 prop to boost the rpms.

2. Drill out the air bleed.

3. Switch to an OS #8 glow plug (currently running a McCoy #9).

Anybody have any advice? Thanks.

Definitely switch the glow plug for starters, and that prop might be a bit much. I'd try a 10-5 or 10-6.
You didn't say how new the engine is. If it is still being broken in, it wouldn't hurt to run a couple of tanks through it on the ground.
Never heard of an air bleed needing to be drilled out on an OS engine.

Also check for air bubbles in the fuel line and air leaks around the carby base, back plate and head