I wouldn't even ask to go lower if it has the lifting mechanism (unless something isn't working properly, or the cabinet is beat up). What a great find you made!
I sold a few of these in the mid 80's when I worked for Singer in Colorado Springs, co at Sew Fro at the Citidel Mall. Haven't seen one since. It is a nice unit, a find.
Good for you, hope you get it.