The inspiration for this GPU support's height adjustment is from the automotive world. Suspension arms and some strut tower braces have a mechanism to adjust length using a single nut which expands or contracts both sides of the nut. The range is 75mm fully contracted to 120mm fully expanded. Hopefully this provides the range you need. Admittedly this thing is a bit overkill in size and the more complicated adjustment mechanism is not necessary but I thought it would be fun.