Hi Brad,
The .62 or 72 should work, the 62 is insanely strong, I flew some of Jimmy Welch's birds with the 62.
Do check some of the older threads for some of Brett's comments on construction of the Strega ARF, especially the wing leading edge. Also, make sure the wing fuselage joint is really good, especially in front. I know of three Southeast guys off the top of my head that had structural failures (some spectacular) from the airplane breaking in half at the front wing/fuselage joint.