Thanks. I searched around a bit and found only one story on this. This stated that the pump on the Astra is physically very close to the rack and this proximity led to pulsing which was noticeable while steering. It was stated that this restriction is the remedy.
So as for me the pump has a good bit of hose before it reaches the pump, I am going to leave that restriction out. If I do notice something, I know what to do
Yesterday I mounted the pump bracket to the car (taking a few tries to cut the carpet in the right places etc.)
Not really visible, but it tilts slightly to one side, but I'll live with that. After the bracket was in place I opened up the carpet around the big hole where the brake booster would mount to on the RHD cars. I had a spare rubber grommet thing which I cut as well to feed the hoses through. You can barely see it in this picture, but pressure hose is connected to the pump, return is loosely in place as I need to position and connect it on the battery side.
Next step: fix that return hose and check final routing of the pressure hose. Torque it all up, add fluid and start the pump on temporary wiring. I need to decide whether I feed the supply wire into the interior and connect it to the main fuse box (one open spot on my car) or whether I find myself a battery mounted fuse/ distribution box to wire it to.
In the latter case, I would prefer a box that mounts to the side of the battery and which has replaceable fuse links...