First time breaking-in engine. Any tips?

Okay would you say the engine is broken in? Or is there still some other stuff I got to do?

Why can't I let the engine idle? Doesn't it have to idle to properly set the initial timing?

Change the oil & filter. Flush the radiator AND engine block until you see clear water running out.
Fill with anti-freeze.
You can let it idle, set the timing and do carb adjustments and any other odds & end's needed and test drive!!