That top area issue is a bit of a "hook" issue - which I don't see as an option in your adjustments.

The fat look is a pincushion/barrel issue, so you could adjust your pin a bit. You may also want to pull your horizontal size in a little bit.

The fact the monitor has different adjustments for 8514A and VGA is kinda fun. I don't know the internal graphics of that computer, but perhaps it sends different signals depending on if you are running in a higher resolution (like XGA) mode? Well in any case - I assume there are pots on the other side of that board that can be adjusted. Since you are right up on the board, be careful not to touch anything else. Ideally, you have a long, plastic screwdriver available.

Could you elaborate on the broken contrast/brightness board issue that needs to be fixed?

I don't suppose this "expensive, almost unused" Compaq also came with a manual that lists graphics modes and refresh rates, did it?

If the adjustments (at a proper refresh rate) don't get your geometry to look right, it is also possible you need to replace electrolytic capacitors on the monitor's board.