Hi
I am also building the Skymaster & plan to use a Saito 65 up front & 56 rear. During the build I have lightenened the structure where possible. Ply fuselage sheeting has been replaced with 1/8" balsa, the heavy aluminium u/c has been profiled & lightening holes drill in the centre section. Nest step is the booms & tailplane which again will be lightened where possible. A good source of info is www.flyingmodels.org which has a detailed build article on the Skymaster with a number of useful tips.