RE: GP Giles 202 (46) engine choice?
My guess is that your Giles would be adequate with the Surpass 70, although I am not a big four-stroke guy. I have that airplane, originally with a K&B Twist Head 61. It was "adequate", but not really crisp, and I switched to a Tower 75, which puts some sparkle back in it. I use a 12x8 APC prop, this gives pretty good vertical, with reasonably fast airspeed, which helps point rolls, etc. I don't do 3D stuff so don't need the big diameter, low pitch combo.
Clair