Well played.
I'd say that the actual key to your victory here was your choice of Silver/Bishop over Loan/Bishop.
Your opponent kept himself off $5 on Turn 3 AND Turn 5 from that choice, and that was critical.
In contrast, your money meant you had a good chance of getting the early Witch, which was the key way to breaking the Highway cascade, and also meant a better chance of getting more Highways faster.