wood sander rebuilding

Hello folks,
are our woodworkers able to help me on?

One of my elder clients asks me to rebuild his cannibalized
industrial wood sander. It is not a toy, weights about 3 to 4 tons,
has a transport belt on the table, and two sets of sanding drums for
the course and fine sanding with belts.
The sanding motors are 50 hp (37 KW) each (seems I'm little out aged: SI
versus. imperial)
The endless sandpaper is 1,32 m wide and 2,5 m long.
The working drums are about 300 mm diameter and little more than 1,40 m
long.
The pivoting drums for tensioning and positioning are diameter 175 mm
and 1,38m long. They have their pivot close to the middle of the drum.
where the tensioning cylinder is.
The electrical plan is unavailable and many parts are missing but that
is not so bad. (My daily bread)

What I need is:
First: How is the appropriate barrel form of the tensioning drums?
One is completely worn and the other some genius turned it straight!
I guess at the moment that I need in the centre 2 mm more diameter than
on the ends and the form is a radius.

Second: What to go with for the valve of the positioning cylinder
that swivels the tensioning drum? A valve with 5 way and 3 positions
with closed centre that makes more sense to me
or a 5 way 2 position valve as the actual?

Third: What is an appropriate oscillating rate of the positioning
cylinder.
I have seen other machines oscillating perhaps tipping the air sensor
every 5 or 10 seconds.
And the supervisor tells me the cylinder bounces faster than 3 Hz.

Sounds that this is of topic but the same client wants me to convert an
industrial table rooter into a copier using the hydraulic copier system
from my lathe which I want to convert in CNC.
Ask me the price of this modification:
Same I need for CNC equipment!

Ballendo gave me the advice to get the mobil machine shop to finance the
conversion.
Well Costaricans say: With patience and a cudgel you even get the green
apples down!
It seems like this is the opportunity.
Good Luck to all
Sven Peter

[Non-text portions of this message have been removed]