67 A body BB K-Frame vs 68-69A body BB K-Frame difference?

I've been told that it's pretty easy to cut the idler arm mount off a 68-69 small block or even 6 cylinder K frame and modify the big block K frame. I've cut off several and sold them to people who were doing it.
yeah, I get that. But there aren't an infinite number of donor k frames out there, and there'll be even fewer if we have to canibalize what few remain.