I've realized that nowadays there are switches present on most modern aircraft which electrically adjust the height of the seating position, and I was wondering if that mechanism was present on the SR-71? The reason why I wonder this is because the pilot's visibility was quite restricted in terms of forward visibility which would only make everything worse if the pilot happened to be shorter than other pilots in the unit.
According to the POH the pilot could indeed move the seat up and down
Its worth noting that the SR-71 was a spy plane and visibility from the cockpit was not necessarily a critical aspect of the design. The aircrafts primary role was to cary photographic and sensor equipment, not to spot things from the front seat.