Pan American was a budget line of Conn from 1917 to 1955.  The old Conn sopranos are sweet sounding but quirky and not as easy to play compared with modern sopranos.  That particular example at least looks like a fully functional horn that has been well cared for.  The "L" stamp stands for Low Pitch, which are the horns you want because the "H" or High Pitch ones cannot be played to modern tuning standards.  The "P" stamp prefixing the serial number indicates that it was made before 1930.  It is a relaquered horn with aftermarket nickel finish on the keywork.  You can tell it is a relaquer because the bell engraving looks faint due to buffing.  There is a risk of damage with relaquers if due care was not taken during the buffing to avoid damaging posts and toneholes.  The results of such damage are excess mechanical play and pad leaks.  This one may be okay and it may need work to repair buffing damage.  You could win or lose on the luck of the draw.