The most critical is getting it primed and started right away. Hopefully your carb and ignition are good shape so you are not fighting too many problems at once. The quicker it starts, the quicker the oil gets flowing through your engine. In my heyday of building engines, I could get them to fire and up on rpm in under two or three seconds of cranking.

Once it does start, bring it up to about 2000 rpm. Have someone watching for leaks too. Get the timing set as soon as you can and run it about 20 minutes varying the rpm slightly above and below 2000.

Now for the rest of the break in might be tricky for your situation. You will want to start getting some load on the engine to seat the rings. Not too much load, but enough to get the oil temperature rising. Typically driving is good for this, but not too much stoplights, steady highway speeds or worst of all is idling or fast food drive thru's.

After finishing the remainder of about a hour with the driving part of the break in, wait until you are above about 500 miles before any full throttle runs. This is a good time for your first oil change too.

Again, remember to get it started right away. Too much cranking is the worst and will wear the assembly lube away before the real oil pressure gets there.