I think I would hone it all the way to the high side of clearance before boring, also you cant bore a thinwall sleeve except within design parameters, geez look who I'm tellin this too, I feel stupid now. lol. Anyway I tried to bore a thick cast iron sleeve in a 300 six and it didnt work, got warm and let go of the block, raised hell with the boring head.
Call LA sleeve and see what they recommend.
BTW what did the shop say about the core plug falling out???