Could you just hack apart the current analog mushroom sticks on the PSX controller, modify the interface between the pots and the joystick to fit into a PC flightstick of some sort, then hack them into a couple of pc flight sticks? This would give you a much larger analog control joystick using the same pots. My only concern would be breaking the pots (since there are tiny comparitively) and the amount of movement needed to move the controls seeing as they were once very short and only needed to move a little ways, but now they are very tall and would need to be moved quite a bit to get the same effect. You would have to find a way to mount it, but that should not be too terribly hard.
Additionally, you could do the PC flightstick hack like we just discussed and instead of putting the flight stick back on, you could replace it with some sort of other joystick without buttons; this may require some grinding, filing, and drilling, but should not be too hard conceptually once you get the flight stick apart. This way you end up using your choice of sticks, the pots and wiring from the PSX controller, and the analog interface from the PC flightstick.
Any thoughts on that approach?
NoBonus