You did well to get Gold. The best I could do was silver. The amount of weapons and ammo supplied at the ports in this game was, in my personal opinion, way too low. I had trains sitting at the ports with special consists to grab every weapon or ammo unit which came out of the ports...and still that was not enough. I only made the extra track bonus about every other year -- only by holding troop trains at the ready. I had to use the 'cheat' tactic of hauling from and to the same station with the same train load to quell the rebellion.
I stayed with narrow gauge, only because I knew from translating the game that this was the best option.
I did enjoy this scenario, although it about beat me up in micromanaging my trains. Lama did not cut us a lot of slack in this game.