Subject: Re: Power-Steering & Alternator Conversions.
If you are paying a reputable dealer then I think in the region of £3-5K to retrofit electronic PAS - someone else may need to confirm. You can fit exactly the same PAS system yourself if you do the right research and know what you are doing for next to nothing, I'm sure AM specialists file the GM logo off their hardware...
Not sure about the alternator conversion - shouldn't be more than £150 as it's a very simple job and the alterator is a cheap part - probably cost £1000 if done by an AM specialist.
You may need to reverse the polarity of the car for both of the above jobs (if not done already) - no problem apart from some of your instruments might suffer.