Grafonola Columbia missing arm question

[Paullowe]

Further to my previous question can some one help with the following?

Tone arms that go down into the cabinet, do they have a consistent distance/length? It would seem that there are some non genuine options that I am ok with. I could make a riser for the base of the arm if I knew the length was ok?

If anyone has one of the right length it would be great!

Paul (noob)