I don't care for masterpiece here. I'd get Mountebank as soon as possible, and 1-2 Traders. Buying Cache with Trader in hand should be far better than getting Masterpiece here, and Trader helps you a lot against Mountebank. Given the opportunity early on, you should trash Copper/Estate instead of Curses so that you can block Mountebank more.
Bishop likely helps your opponent more than it helps you, but if the game runs long enough the extra points could pay off.
When the curses get low, consider getting a Fortune Teller on a $3/4 hand. It's practically guaranteed to topdeck a bad card, and outside Haven (dubious at best) there's no way to get big hands here so having 1 bad one guaranteed is significant.
I wouldn't buy Village, but Inn is a reasonable purchase to get a Mountebank in to your upcoming hand before a reshuffle.