The best fully mechanical 35mm SLR ever built?

Certainly one of them. The F2 was the second, and last, fully mechanical hand-built F; introduced in 1972 and superseded by the electronic F3 in 1980. Aside from the expected minor tweaks to the body, during the eight year production run, the only part which needed battery power - the finder - was developed over time to provide more responsive metering and better integration with lenses. The F2 body barely changed and any body from 1972 will fit a finder from 1980, and vice-versa, giving the camera its designation of, eg., F2, F2SB, F2A and F2AS.

The F2AS is the last of the configurations, with the F2 body connected with the AS (DP-12) finder. This finder is essentially the same as the A (DP-11) finder but with lens coupling for the new (introduced in 1977) AI lenses which superseded the "bat-ears" prong aperture coupling of pre-AI lenses.

The meter is a simple LED readout of over, correct, under and operation is fully manual. A battery is required only for the meter and if one isn't required, a more compact configuration is to replace the AS finder with a DE-1. This is nothing more than a basic prism with no metering nor readout of any kind and, as such, is very compact.

The F2 is silky-smooth, very sturdy and a joy to use. When there are no features to get in the way, the basics of manual photography become second nature. A true classic.