74 Hood on a 73 swinger???

I'll admit I've never done the swap myself (I prefer the Dart beak in any case), but I'm 99% sure the only difference between the Dart & Valiant fenders in those years is the placement of the blinker lens- Valiants have them below the bodyline. And I don't see why you'd need any special bracing.. the Valiant doesn't have any, and they're essentially the same car (especially in the later years).

Here's a '73 Scamp- basically what you'd end up with.