What about some of the Marshall corners?
I can't remember what the radius is on the Origin heads. If it is normal Marshall 3/4 inch radius use the plastic Marshall corners. If it is 1/2 inch radius use some like those 2 screw Mojotone units. I've used those before. Amplified Parts in AZ has all that stuff and is closer to you.
Looking at the pic of your Origin, it looks like a 1/2" radius. And yeah, look at Mojotone or AES/Amplifier Parts.