This approach paid off as I started booting at random walls where the lizard fellow wouldn't normally wave his arm. Finally, progress! I then tracked down the tunnel with more miscellaneous door booting and found the entrance to the Main Control Sector.
As I'd first posted, I came prepared with all of the cards and the Ultimate Adventurer status - so I saved, gritted my teeth and began plowing through the waves of Terminator bots.

After much resting, I got to the terminal with the secret word but couldn't seem to open any of the other locked doors within the area. Regretting my decision to go for a ninja instead of a rogue yet again, I pulled all the levers I could find and entered the bay as Corak intimated. And there it was! The end sequence. It felt like a huge relief, let me tell you.
I experienced more pleasure from completing Might and Magic III than I did from Morrowind, just last week!

My humble final score was only 783,009,749 - a smidgen of what can achieve, as I noticed a '0' in front of the first 7.
In the end I only found 21 UPO's and a few more after the event of giving 11 over to king Tumult, which wasted a fair bit of potential xp. But in the end, I was running out of money and couldn't afford to train, hehe, even Lone Wolf abandoned me deep inside the Central Control Sector.

In conclusion, a brilliant rpg, much enjoyed due to its longevity and challenges. I've completed MM's 3-8 now. Only 1,2 (on my C64) Mm9 and Swords of Xeen to go.