Motorman chimed in as I was writing this, and he is correct. BC to Outer Hole on flap horn. The Banshee was designed for a 3" bellcrank. Is yours 3 or 4" Also, are you using nylon horns vs a one-piece metal? Both are going to require a cutout but with the 1-piece metal you can make a wide TE Faring/Fillet on each side and position the horn so that the controls are over it. This keeps the flaps without a cutout, you maintain your original size ratio and cut down tail wiggle just a bit. Ratio of 1:1 is good but 2:3 might be better (30 Flap, 45 Elevator) depending on how you fly corners. It is 100% personal preference, but I don't like only having as much control as you need for normal circumstances. Dennis is also right, 30 - 35 degrees on the elevator is probably about 5 degrees more than you will use but it is also all you will have if you really need more.
Ken