Disc brake hoses don't fit frame brackets. Grind which one?

Yes, you could have bought the wrong hose. Or rather, they could have supplied the wrong hose. My experience is that, starting in the mid-80s, all the listings for A-body brake parts became filled with errors and omissions. You can't trust any supplier part listings -- you have to compare it to what you have.

That said, I don't see why you couldn't grid a flat on the hose end. It's an expendable part, and if it works, it works.