I'm with Dan on this, I usually use a couple of lenses when out with a Graphic, I have a working Range finder set for a 150mm on my Crown graphic but far prefer to use the GG screen. Often I use a 135mm Symmar so the range finder is useless and my second lens is a 90mm Angulon, often I carry a 203mm Ektar as well..

Why do you want a Speed Graphic ? Unless you want to use barrel lenses there's no real advantage, otherwise why not look at the Super Graphics, they are a real step up in terms of flexibility, a revolving Graflok back, far more movements and a great all round work horse of a camera.