I bought a cast aluminum one from AJ. Fits the motor fine; good quality and price.
The problem is that it's really tall, and very square. The later 258's are taller blocks I think, and the 1970-1972 Hornets have a cowl sheet metal protrusion that houses the wiper motor -- this interferes. Later cars don't have it.
It's a bit late now, but there is a simple fix -- re-drill the motor mount pads on the x-member 1/2" forward, and move the motor/trans forward. (The rear trans mount, I could never find the correct part -- the horizontal ear part is too long; I had to cut and redrill. Had this same problem with the 75 Gremlin. THe part looks correct, just one dimension off. Would ahve to redrill the rear mount too.) There's no strength/safety issue, as the pad is plenty big. It would however shift weight forward. All of these cars are nose-heavy enough (I may go do SOLO II again with this thing).
But since I had clearanced the valve cover before, I'll simply redo it. Hopefully there's enough room to do this.