Just tried once more, with a fresh disk (the 15'th I tried), and a fresh download of 10.12 incl. the common CTF.
As well as changed the drive in the console.
And finally it worked, after initial setup the custom CTF I made worked as well, so it seems to have been a combination of 3 things:
1: bad floppy drive in the console
2: a bunch of bad disks
3: a slight tired techie around 3:00 AM
Before it stalled at the startdisplay with the Bios version + age.
Bottom line of the display where it shows how far the upgrade has progressed, was stuck with only a ( on the left.
Oh and the console is the old without VGA option.
Anyway it has returned to life, and the one in charge of the money is happy we can skip getting a more modern console for now