Sara,
The 46LA has an airbleed carb if I remember correctly. They add just a bit of bother to handling but not much else. And inverted engines don't always need their tanks lowered. What they all need is to sort out your fueling and choking steps. Those steps are really far more important to getting an engine started than most people think.

Once the engine is running, does it throttle up without stumbling? If it stumbles, adjust the airbleed until it doesn't. Airbleed affects the dependability of starting a bit more than a lowspeed needle does. If an airbleed isn't adjusted, those engines can be a pain. It's gotta be right before you'll have a chance to find out what else could be wrong.

Someone mentioned turning the airplane over to crank it. This takes some effort to do. But it's an excellent test to prove or disprove if the inverted installation is hurting. Find an old control line flyer, especially one who flew stunt, to help. Good chance he'll know how to safely and surely handle the airplane.

Do you know how to safely turn the prop through till it bumps? It's often used to finger choke the engine.

But with most airbleed carb engines, using an electric starter and a proper throttle setting often works straight out. Just fuel the plane and set the throttle about 3 clicks from closed. The carb will be almost closed. With an airbleed carb, this causes the engine suction to be more than adequate to pull the fuel lines full. That is, if you're using an electric starter in about 3 second bursts. Some airbleed carb engines actually start best with the throttle either one click open or at the minimum idle setting. But they have to do this from "dry". Dry means no finger choking.

There are a couple of ways to finger choke. Most everyone knows the "finger over the venturi" technique. Put one thumb over the venturi and with the prop FIRMLY held, turn the prop a few revolutions. Don't flip it. That thumb is in danger if you're not holding the prop securely. Another way is used when you're running muffler pressure. Simply put a finger over the muffler exhaust pipe and turn the engine through a couple of times. If you have a holder who's helping start the airplane, have them reach up with a spare hand and seal the exhaust while you're applying the electric starter. As soon as the engine fires, uncover that exhaust. (Or the engine will do it for you........ truth is, you're wanting to let go as soon as the engine shows life, or you can see the fuel line fill.)