Stripped the scrap "Geze 2000" German opener to see its guts. See pictures
It is a very solid bit of engineering with next to no lash, The pinion is on needle bearings both sides, the pinion has 41mm available free movement and the rack cylinder looks like it has plenty good metal either end to attach arms somehow.
I am NOT going to use this as a steering rack on this Kart, I am going down the Pitman arm route after a couple of conversations and some reading in fora. The spring is available if anyone needs one, I will post UK.
The lever arm was what I started looking at when I was looking for a ready made Pitman arm and may be used as the splined end might give me a bit of adjustment to align the steering wheel if I mess up.
If anyone is interested, I have one of the site guys on the lookout for different dead ones when we replace them and I might look at the comparative rack lengths from different brands. To achieve clearance with this short a throw on the rack would have proved difficult at the steering arm end.
If anyone does go down this route, I would be interested to hear about the results.