ORIGINAL: Missileman
Thank you all for your input.
Yes I do need all the advice I can get (I have yet to solo my trainer so it won't be until late summer before the 4* flies "with some luck")
I did come up with yet 2 more options.
Super Tiger G90 and Magnum GP65 SE (older one made by Thunder Tiger)
I have read reviews that say the 4*60 is tail heavy so maybe a bigger motor would be the ticket (better than dead weight?)
All of the two strokes you've listed will likely be very similar in weight. The majority of .90 and .91 two strokes are just bored out .61s so the weight difference, if any, would come from the bigger muffler on the bigger engine. SIG estimates the weight at about 8 pounds. The 70 four stroke should pull it around well. No hovering or other 3D stuff but 4*s are not 3D airplanes. For graceful basic aerobatics any engine you listed would be fine.