Hello!

I thought, that what is maximum hight limit for a pilot at a B757?

im not exactly sure but for the air force the height requirement is 78 inches

wouldnt that mean you would have to be 6'5" ? that tall for a minimum requirement

All USAF, US Navy, and US Army cockpits must be able to accomodate aircrew from as small as a 40th percentile female (5 ft 2 in.), to a 95th percentile male (6ft 5 in.).  For some procurements, the US Army may go as small as a 5th percentile female.

There are many many other anthropmetric measurements for each of these percentiles, like sitting eye height, hip to foot length, sitting arm reach in multiple directions, etc etc.  Also strength measures to that set the maximum allowable forces on cockpit flight controls.  Many of the cockpit requirements must be met while the aircrew is wearing an "air warrior ensemble".  This includes flak vest, survival gear, helmet, NBC (nuclear, biological, chemical) mask and gloves, and much more.  It's pretty comprehensive and very complicated.

Hope this helped.