I'd start by trying new fuel and glowplug; no need to introduce more variables. I've definitely had cases where a glow plug glows, but doesn't run right. Also, if you leave a sealed plastic container of fuel on a cement floor for a long time, sometimes you'll notice wet nastiness under it when you pick it up. *Something* happens to it while it's sitting there.

Depending on your setup you might not draw fuel by flipping the prop, but you definitely should if you choke the carb while you flip it.

If the number of turns you're giving the needles don't come from instructions for your particular engine, play around with them. 2 1/2 turns is typical, but if nothing else is working try 4 or 5. No harm done (just don't hydrolock it, but you're suspecting that it's not drawing well enough now.)

Have you got a local engine guru to play with it yet? Often it's obvious when an engine is starting way too rich or too lean by listening to it.

How do the bearings and compression feel?

If you want to take it apart and clean it, it certainly wouldn't hurt. Crankshafts and bearings tend to rust a *lot*.