fake can aften be noted by the flutes as well , in how they are cut , the shape of the turnout and tip , the mkI as noted were only made by singer and with only 75000 made in early to mid 1941 , they would be the least likely to have been mated to your `1950' LB and also as stated with the mkII being the only one made outside britan [ie; canada & us] it would be best suited