Rebuild is surely much worse than the engine here. The engine involves just about everything except rebuild. It especially uses watchtower! I am not sure exactly what order to buy things in, but eventually you want to be drawing everything and getting multiple provinces. Get plenty of actions with plaza/squire, and then you should be able to get your hand down to just a watchtower and draw 6 cards, maybe with an apprentice play at the end.
If you do decide to go for rebuild, the only 5-costs you want are rebuild, duchy, and a single count. No apprentice.