RE: Goldberg Ultimate 10-300 build
If you aren't comfortable with the soldered cable fittings, you can also go with DuBro's pull-pull kit. It uses crimps. I have used the Dubro on other planes, and it works fine. I don't think I'd move the servo back away from the original plans, as it will move your CG back too far.
For anyone just starting this kit, there is an easy way to make the top wing line up perfectly when assembling at the field. Higley's Bipes book outlines the idea of adding a couple pieces of ply cut to the shape of a "U", which you glue onto the structure of the wing. They are fitted to guide the sheet metal braket so the holes for the assembly wire line up perfectly with the holes in the sheet metal braket. No fishing around for the holes.