If your max speed was 28mph you are going to be just fine with a 48 or 50 ... a 52 is nice though for long descents.
My highest gear is 52/11 and I use it seldomly.
You say you spin out ... was that on 26" wheels with typical mountainbike gears 42/11?
You only use 2 gears mostly and you basicly only shift in front? That doesn't sound good since shifting in the back is smoother.
Try getting a good cadence of about 80 rpm and try to find the right gear for the right situation.
Are you serious about the "45 degrees"? That sounds insanely steep.
If you are certain that 34/25 is low enough for you ... go with the rapid 1