I'm not so convinced by your detour over the IW/GH. You want to Curse asap to have the greatest effect, in a mirror to win the split, against BigMoney or an engine to disrupt the buildup as early as possible. When the Curses come later they find a larger deck in which they have a smaller effect.
Nevertheless, you are on the right track with the Bureaucrat. In an IGG mirror a single Bureaucrat is a slight help. Bureaucrat is often strong in Curse games, especially with weak curses like SeaHag or Young Witch, that have only a weak effect on your own deck. This is because these games often turn into
slogs, in which Silver is a very good card, your target is more Duchy than Province, and in which Victory cards are relatively long in the deck (compared to a strong engine that buys most of them in the last few turns), so that the attack can work of.
I would say an IGG game is on the edge of that, it also focuses on Duchies, but the deck is quite strong in itself moneywise even without Silver. But still you would take a free Silver anytime in these games.
edit: Ignoring all the other things on the board just focussing on the IGG game, I could also see starting with IW to gain Silvers, with the option of GHs in lategame to be not so bad. IW into Silver with the same idea as why Bureaucrat for Silver, with a +1coin on gain and some flexibilty for the IW.