This question has been hashed over a few times here. There are several options. Linkages can be bought (see the 12 Port Advertisers for a start). A cheaper option that has worked for me was to get a throttle cable from a Harley shop. They come with a 90 degree turn, which works well when placing the carb "sideways" as opposed to how it would go on a V motor. Some here don't care much for cable linkage, but I've had no problems with mine. I made the brackets which was pretty straight forward; not much is req'd.
