IMO the Saito .72 wont give you what your looking for in that Giles. I had one and it had a .91FX in it and it was OK......

Plane is too big to really perform on a .72
Saito 1.00? Yes.

Anyone who know me on here knows what a big Saito .72 fan I am. I am no way bashing that engine.

And you are correct in your statement about tuning a 4 cycle by ear. To do it right, you need a tach.