I bought my Score already built with new controls, fuse mounted landing gear and a Saito.56 in the nose. I can't tell you how difficult changing the controls are, since I didn't do that. I did have the nose on mine come apart in flight, which I have detailed several times here already so you can search for it. You can probably pick and and scrape out the hot glue in the nose section and flow in enough C/A and this epoxy to get it solid and reliable and that pretty much includes the tank area. The covering on mine is fading fast now, doesn't match where I repaired the wing and nose from the nose separation event, and a recover is on the horizon. If your covering is intact and in OK shape, I would leave it on until later, unless you just can't stand it and don't have anything else to do. As far as controls, just look them over and make the decision on changing them. If the wing is still a bolt on afair, that's not too much of a problem. If you change the controls and like the way they turned out, you might want to glue the wing in after you are finished and test flown. After a lot of flying, my wing was no longer solid and had some play in it, so I glued it on. The airplane is not meant to be a take apart, this is just how the engineered the assembly. Mine weighs in the 70 ounce range and flies quite well with the Saito.56. I would not recommend anything smaller that a ST.51. A lot of the weight in mine is in the engine, but that may be needed for balance if you went with a lighter engine. If you have a ST.60 that would be a good engine for it.
Type at you later,
Dan McEntee