I am usually overkill with engine/plane combos but....

I just finished teaching a friend how to fly on a very similar airplane- his has an OS-65LA (yup, bushing not BB's..) and it will hover!

Not that it is necessary but it has plenty of power and was the easiest engine to break in I have ever seen-

The OS-60FP is the older version of what is now the LA series... The Saito-72 is a great engine, but will not have more power than the 65 2 cycle- The MVVS-77 & 90 would not be necessary on this type of plane-

I would say get an OS-65LA or a 61FX (Lasts longer..) or if you want to try a 4 cycle- look at the Magnum 91.... Bang for your buck!

Good luck and let us know what you decide and how it works!

james