This information is right out of section 32-530 "Checking pressure oil pump and level controller" of the MB series 123 service manual .

Guarantee basic pressure 30 bar + or - 8 bar .

I believe that is around 450 psi .

I would think that is enough pressure to effect the ride height, I'm not sure how much though . We need someone with a working system to crack their bleed valve and see how much the car drops .

They explain in the manual to check the pressure you hook a gauge up to the bleed screw spot on the controller . With the engine running move the disconnected SLS lever up to fill position . When the gauge goes up to 130 bars .Return the lever to neutral . That is the minimum amount of pressure that needs to be produced by the pump . They say not to bother to see what the max pressure is . Next , stop the engine , set the lever to empty[down] and read the gauge ,wait 5 min. read again, wait 4 hours read again . Leave on overnight , read again . " The basic pressure should not drop".

A far as setting the ride height by adjusting the connecting rod , they say don't do it . It makes the car unstable around alternating bends because the damping force of the spring struts is reduced . Also if you drive with a lot of weight in the car the max pressure is met and you could here the pressure relief valve popping or hissing along with oil flow and knocking noises .

The SLS lever is set by using a 4mm rod through the locating bores on the lever and valve body . With the connecting rod disconnected and the car running . Move the lever up to fill . When the car raises up move the lever down to empty . Turn the car off, move the lever up to the point where the 4mm rod will line up through the bores .If your car is sagging and you do have basic pressure in the system something else is wrong .

And here is a sentence verbatim right out of the manual .
"If the level is to low in ready-to-drive condition of vehicle , correction should therefore be made at rear springs."

There is also a whole bunch of stuff on checking the trailing arm positions in relation to proper vehicle level . This seems to be beyond most people ability as there are a lot of special tools involved .

Hope this helps . Spike.