So, it occurs to me that in a pure two-person FG rush, the FG pile runs out VERY quickly, right? It's impossible to draw less than $2 if all you buy is FGs, so you can put a hard limit of turn 5 to finishing the FG pile if that's high enough priority -- each player could just buy FG every turn from turn 1 to turn 5, and that kills the pile.
Thus, if you're talking about something to "win the FG rush," you need to be talking about buying something that gets you two FGs before turn 5 (one to replace the lost FG buying opportunity where you bought your "enabling" card, and one more to actually get back up above parity).
I don't think that there exists a card in the game which, with one play, gets you two FGs. So you need to be talking about a card that you play twice before turn 5. Obviously, this needs to be bought on turn 1/2, then played once in turn 3/4, and then again on turn 5.
If you're the second player, this is hopeless -- there's only one FG in the pile come your turn 5. Only the first player can hope to do this. And he needs a substantial amount of luck.
Probably more realistically, you could hope to get a card that lets you retain 5 FG parity (particularly if you're player 1), and will be useful to you later in the game. So, Workshop strikes me as a bad FG "enabler" -- you're unlikely to get more than 1 FG with it, and it probably won't be particularly useful in the late game. Remodel, on the other hand, probably lets you retain parity and you can then turn FGs->Gold and Gold->Province, so that's cool. Bridge or Salvager also seem promising. Remake seems impossibly bad -- won't even let you retain parity.
All of this changes if your opponent is not monomanically focused on buying FGs. So that implies that if you see your opponent open Remake or Workshop, you can punish him by buying FG every turn.
This is also a case where first person advantage is quite strong.
