Richard, I regular Y harness will not work with the servos in the tail. You need some way to reverse one of them. I suppose you could mount one servo above the push rod center line and one below if you have the room. Most are done level to each other and one has to be reversed. I fly with a Futaba 9C and it will do it. It all depends on the radio.
The length to the elev halves is not critical. Most are mounted in the area under the stab for two reasons. One is ,there is normally some strength in this area for the mounts. Two is, it hides the servo from view when looking down at the airframe.

pics in next post, David