Speedway is one source. Also Ken CT on this forum might have components. I had the best results running them in tandem with straight linkage. I could not get a pair of 94s to run well progressively. I was not able to get the secondary to seal well when closed.
Yes the link is adjustable. Set the throttle arms leaning forward at 45°. Sync the carbs at idle with out the link connected. Then adjust the link to match the position of the arms. You should be good to go.