You'd be better off buying four M models, preferably with at least one with 180hp conversion, refurbish two, make shine for school, use the other for self and one for parts.
I owned and flew several through to the N model, flying school and charter. My first was a '65 F model. Those early ones were light and much better cross-wind landing especially with no wheel covers, they had no cuffed wing leading edge and a much smaller fin strake. Latrobe Valley Aero Club had M models for years and were still in service after twelve thousand hours or more. I'd pass the late '80s models, after the ten year production hiatus, they had 10 underwing fuel drains, what a pain.