I had the same plane with a Saito 170 radial, a DLE 30 should fly it nice. You wont need more than 1/2 throttle most of the time. Valley View R/C recommends 18x8, 18x10, 19x8 & 20x8 for the 30. If you have the ground clearance a 20 x 6 or Vess 20A would be a good choice. That's a draggy air frame, you want a lot of pull but not much speed.