A 60 is just fine for the Kadet SR, we have several here and they fly just fine with .60's and even some with .72-.91 Four Cycles, plenty of power if you need it, you can always throttle back

Kadet SR Specs:

Wingspan: 78 in.
Wing Area: 1150 sq. in.
Weight: 6 lbs.
Length: 62 in.
Wing Loading: 12 oz./sq. ft.

Goldberg Protege 60 Specs:

Wingspan: 71.5 "
Wing Area: 860 sq in
Weight: 7.0 - 7.75 lb


Great Planes PT-60 Trainer Specs:
Wingspan: 71"
Wing area: 888 sq. in.
Length: 53.25"
Wing loading: 18-21 oz/sq ft
Weight: 7-8lbs.


Clearly the Kadet SR is best suited for the .60 size engine class, look at the Wing Area, and light loading. Good Luck, Good to see a new guy wanting to build! Go for it!!! Have a blast.