Andrew,
I've broken in and flown several Saito's, from a .40 to the .72, and I no longer worry about choking it down with a throttle or anything. I simply mount the biggest prop that will fit during the initial break-in, and the prop load by itself limits the RPM. For example, to break in my .72CL, I used a 4-blade (!) APC 14x10 that I had laying around (don't ask why), and fired it up on stock venturi and a 10% nitro fuel. The engine developed only 6k RPM or so. After 2 tanks, I switched to a 14x8 Zinger; the RPM went up to 7k or so, and I ran it for 3-4 tanks like that. Then a smaller prop, etc, etc. The last run was on the intended flying prop at target RPM, and by then the oil coming out of crankcase was clear, which is a sign to me that the bench break-in phase is complete.
Hope this helps.