Conversion question: Marantz SLT 12 into SLT 12-U !

Hi folks,
I am planning to convert my Marantz SLT into a SLT U-version.
What are the problems?

1.) I need a weight of the upper arm from a U-version. The standard version has only
a weight on the lower control arm.
Or I need the dimensions and informations about the kind of material the weight is made off.

2.) I need an alignment information for the U-version arm assy(how to deal with the upper weight?).

3.) I need a u-Version headshell from a junker or some dimensions to make a reproduction.
I need the dimensions where the arm enters the headshell.So how much inches/mm is it to the corners
of each side (edges of the right headshell side)?

4.) There is a magnetic plate between cartridge and the top of the headshell. Please give me the dimensions.
It is mounted with one screw.
In the case of reproduction a headshell I will remove the magnetic plate, wanna save weight and magnetic
influence. I am planning to remove the magnet in the arm housing!

5.) U-versions have a black foot-assy between cabinet and arm housing.For what is this for?
To have  a "hiigher" door?

6.) What is the lenght of the tonearm between headshell and arm mounting. It seems that the U-version
has a shorter arm because of the wider headshell.

Many thanks in advance,