The engine seems pretty weak and I guess it should loose to Rebuild and Embassy-BM. There's really a big lack of +Buy or a gainer for Highway to be good enough.
Embassy/BM is superfast and could get 4 Provinces in 12 turns if things go well, but Rebuild really loves that extra Silver. I don't really know, I'd guess Rebuild is still better and go for it.
And I really wonder how your opponent could get to 5 Provinces after 14 turns with this strange deck.