If the wagon carb is a 460 not a problem (even if it was a 400 still OK) Ford carbs from back then ran about 20% rich any way so don't worry about starving it for fuel. There are applications for the PI carbs. In fact if you bought a carb kit for the one off of your wagon the kit will come with instructions that apply to ALL the cars that would use that carb. The carb would be the same/similar but the internal adjustments are what makes it different based on it's application. I hope this makes sense.