Here is another vote for running on a test stand first-set up when you have nothing else to worry about-concentrate on getting the engine broken in properly, following the mfgs recommendation, generally, or some of the great threads posted on RCU. After all an engine is a decent investment-do the break in correctly and you will be rewarded with a sweet running engine and minimim problems at the field.
I see a lot of flyers at the field, tinkering and puttering around with engines. Three of us that fly together all break in engines on a test stand, and when we go to the field, we fly, fly. Not to say you will not have an occasional problem, but it cuts the odds.