In my day the takumar 135mm f3.5 was a very slow lens that had to be stopped down to f8/11 to yield sharp results. 35 mm format I would avoid. The medium format lenses however is a different story
Ok thanks chaps.
Gutted I sold my Pentax 67 kit now but I'll go for the 6x7 lens as I guess there will be a larger "sweet spot" and more back focus leeway for filter wheel etc..
Given the size of the 414's sensor , some 6 x 6mm, unless you want a longer flange focal distance, I wouldn't go for medium format lenses, esp, vintage era with potentially lower spec glass and the potential to amplify optical aberrations more, compared to new-ish fullframe or APS-C lenses, which now will routinely use ED glass and modern multicoating and modern optical design and manufacturing methods.