Just a comparrison:
We stuck a fairly new motor in the boy's mustang and it was smoking and using a bit of oil.
The motor was supposedly fresh when we bought it (less than 500 miles), we did what your engine builder recomended.
The only alternative we had was to yank it and do a rebuild or run the piss out of it, we choose the ladder and it has all but quit smoking and using oil.
Sometimes moly rings take a bit to seat up anyway, this process can be aggravated by an incorrect hone job from the machine shop, a moly ring likes a smoother final hone where as a cast ring likes a rougher one." I think" not real sure but a good machine shop should know the difference, ask them to be sure, anyway mismatch the 2 and you have a recipe for a oil burner.
Sometimes they will go ahead and seal up, sometimes they won't.
I've also heard that pouring alittle tranny fluid down the carb while runnig will help the rings seat up too, I dont know about that one either, maybe just snake oil.
JMO, Cp