Your engine will run very nicely. However, it will not have the same peak RPM level as the FS-120 Surpass (with or without the pump) series. It should run in the mid-to-high-8,000's when propped with a 15 x 8 prop or so. The RPM will vary considerably, depending upon the brand of propeller.

If it needs parts, you'll have to scrounge for them. O.S. has not had parts for that engine for about two decades.