I'm in total agreement with (cllaurit). Tipo's had large rack driven servos (at least mine did-PLS 15 I think) these servos had a whoppin 10 to 12 in/oz of torque. One point to remember is these ships need very small movement of all the control surfaces 8 to 10° on ailerons and roughly 10° to 12° on elevator. After all this is "Ballistic Pattern" so at 130mph the control surface doesn't have to move very much to do a very good job. Back in the day, "Flutter" was an ominous calamity always in the back of my mind at least. Long torque rods made of 5/32" music wire to drive the 'Barn Door' ailerons instead of belcranks eliminated alot of slop in the connection.

My last recommendation is I will be going with ball bearing servos, but for me and my house, I want small, light and something in the 20 to 30 in/oz range. A Ballistic bird that was weighing 7 to 7.5 lbs in the old mag's could easily drop a lb to 2 lbs with the modern servos and batteries.. JFYI IMHO