RE: Good Engine for 90 size edge 540
Had the same plane with a Saito 100 here in New Mexico (4400')...and it barely had enough power to get out of it's own way. Forget 3D...in fact, forget aerobatic's period!
Then put a Saito 180....and that was the ticket. It was a fun plane then...
Just my opinion...high altitude really kills power.
Mark