Oh you have a throttle...great! I always just flew mine flat out. So you'll need a third servo. Micro servos will work fine for everything including throttle. I'd use 1/2oz servos all around. The throttle linkage for those is usually just a thin piece of music wire.

Don't get carried away beefing it up just because it has a glow engine. Even in the old days RC models with Pee Wee power only weighed 6-7 ozs. The engine really doesn't stress it much. The 1/4 inch stock I recommended is actually overkill. You could use 1/8 inch. The main thing is fuel proofing, not beefing up.

You're plane should weigh about the same with a Pee Wee as it would with electric power. The battery for Rx and servos can be very light. The engine is very light. No worries.

Jim