Hi Mosin,
I don't leaving a newly-rebuild engine idling is good. I have heard of them seizing up after this. I believe in the early bedding in of the rings (having put them in dry, with just a bit of light oil on the skirt). I used the "Klaus" method - of "stationery" running in. After that, no:-
- excessive idling
- high revs
- lugging in too low a gear
for the first 500 miles...