I'm installing pull-pull cables on elev. and rudder to hide the control horns. My question is, does the bellcrank that I hook the cables to from the control surface have to be the same distance apart(attachment points) as the horns on the control surface? This is my first attempt at a pull-pull system,andthe feed back would be appreciated. Thank you.

Ideally, yes. If not, there's a gearing effect which might be noticeable in tension in the cables, and motion relative to the angular travels.
Close is good enough most of the time.