I help designers improve their games.
I've change it to use 1 to 1, but one of those which is already on the price. Let's say when changing a settlement to a town 3 grains and 2 ores can be used or 1 grain and 4 ores.
Tested it today - works fine. Doesn't give big so huge advantage as before.
That seems very clean. It keeps the flavor of the card, without undermining a core mechanic of the game (the fact that certain resources are only good for certain things). Very nice!