RE: S.E.5a Biplane
A friend and I each built the 1/4 scale pup according to plans and both came out very tail heavy. We had to add about a pound of lead on the firewall to balance so I would be very careful on adding additional weight in the tail such as servos and other radio equipment. We each have G 23s as power and it is more than adequate for flying.
Good luck on the project, you will enjoy it when finished