Approved full throttle range is 5000-6000 RPM. That motor has a magneto, so I don't know of any tach made for it any more, except inductive tachs such as Tiny Tach.
EDIT: Happily, it appears there may be some new stuff out there that I don't know about. Faria #32805 and 33817 are advertised as being Universal for all outboards. There may be more, I dunno. Call iboats for more info.
