Leave the flaps on... flaps on a Kadet are interresting, even if unnecessary. Its kind of fun to put on full flaps, point the nose relatively high, add a bit of power and "hover" in place in a 5 mph wind. (not quite the same as a 3D hover... but same effect...)
Just a little bit of flap defelction goes a long way toward eliminating any chance of tip-stall on landing approach. The 2-ft ground roll of a Kadet Sr with flaps is great.

The Magnum .61 is a bit more than the plane needs... It can fly on a .35 from the mid 1970's. (less power than most modern .25's...) With the large engine, the thing is a heavy payload lifting model... you can easilly drop 4 GI-Joes with parachutes. (the old 12 inch tall ones) Most of the time it will be very happy at 1/4 throttle. (it will take off at as low as 1/3 throttle)

The fuel tank... yes you want to have the clunk make it to the bttom of the tank.... you dn't need it to make it to the front. (they tend to get stuck there if they do make it.) one of the heavier sintered bronze filering clunks may be what you need.

The lighter fuel tubing is made... It comes in the Goldberg ARF fuel tanks, among others. Sorry, but I don't know where to get it. (might e-mail Carl Golberg Co....)