Gary,
45°-45° was popular for a long time. It may have been the intended proportions. Have a Magnum manual around here somewhere... Don't worry about the 45° angles shown - you'll never get them that far. It IS a good idea to make the controls free and equal past where you'll ever need to go. It won't bind up on you, that way.
Quick check: The flap and elevator control horns should show on the plans side-view. If the radius from hinge to pushrod hole is the same at the flap horn and elevator horn, the flap and elevator angles are the same. I'm talking about the rear pushrod, not the one from bellcrank to flap.
Magnums flew well, and far as I know, most were built per kit instructions, unless the builder had some special ideas.