Okay, after much p-balling around I decided to ditch my idea of a home made SW yoke and try find a decent off-the-shelf alternative.
Currently I'm playing around with e-dimensional's Gyroscopic-Pad and it might just work - (I definitley prefer it over Microsoft's Dual Strike, but when they fine tune the script for the wii controller it could be the daddy).
Anyhoo, just a couple of problems so far - first the calibration is tricky using the "twisting the yoke to the extremes" method, in fact it's impossible in analogue mode, though switching temporarily to digital mode seems to get close.
As for up and down, I can't remember how the arcade works off the top of my head, but rotating the pad forwards and backwards seems to have the opposite effect of what I'm expecting.
Anyone know how to switch this over - and no, there isn't an option with the Joypad's software or drivers

Many thanks in advance
Joe.