The 65 was designed for left-hand tractor prop, see here;
http://www.spitfireperformance.com/griffon-65.pdf
Possibly the one you saw is a 65 with bits of a 58 incorporated, 58 parts are easier to find. If the engine is ground-runnable, then a cut-down contra prop is used, but that would be from a Shackleton. Sorry if that muddies the waters even further!