Here is a link to the UCD 60 Manual from GP.

http://www.greatplanes.com/manuals/gpma1270-manual.pdf

4 7/8 inches back from the LE of the wing is initially correct (as per Great Planes).

I just finished building mine and I've got serious tail heavy issues with mine. It currently balances out at about 5 7/8 inches back from the LE of the wing. I trying to decide what to do about it. It looks like I need more than 6 oz. in the front to balance. Has anyone tried a Harry Higley Ultra Heavy Hub? Any recomendations for where to place weight?

Here is the control throw recomendations from Great Planes:

We recommend the following control surface throws:
High Rate Low Rate
ELEVATOR: 1-1/8" [28mm] up 3/4" [19mm] up
1-1/8" [28mm] down 3/4" [19mm] down
RUDDER: 2-1/4" [57mm] right 1-1/4" [31mm] right
2-1/4" [57mm] left 1-1/4" [31mm] left
AILERONS: 1-3/8" [35mm] up 7/8" [22mm] up
1-3/8" [35mm] down 7/8" [22mm] down
3D Control Throws
NOTE: The 3D control throws are only meant to be used
for extreme aerobatics. These are not meant for normal
flying. Be confident using your dual rate switches before
utilizing these rates.
ELEVATOR: 3" [75mm] up
3" [75mm] down
RUDDER: 4" [100mm] right
4" [100mm] left
AILERONS: 2-1/8" [55mm] up
2-1/8" [55mm] down