Need help on correct linkage.. who makes it
Look for something like this that fit's a demon carb. I don't know if there is such a animal. That demon throttle plate looks pretty wonky. A stock 4 barrel bracket should work fine for the cable to attach to. Start a wanted thread for that. No one repops those as far as I know. Also, I am not a fan of those air cleaners. One backfire and you send melted plastic down your carb.
The cable isn't hooked up to the carb but you can see the bracket.