Just an update, got the car back with its new FI Pump Friday, it ran ok, but not great - e.g. a few hiccups when trying to maintain a constant speed. Went back and had the mixture leaned a bit + a broken spark plug replaced. Now it's 99% there, the remaining 1% is most likely due to wear in the distributor shaft, which will be fixed later when the electronic ignition will be fitted anyway. For now, I'll just enjoy it for the rest of the summer.
The old pump will be sent out for restoration during fall/winter.
My mechanic rectified a lot of faults made by previous mechanics (and myself) - wrong type of condensator, leads with build-in resistance making the spark extremely weak etc. So hopefully the 2+ months and quite large expenditure will prove to have been worth it.
Again, thanks for all your helpful comments, advice and suggestions - they have been priceless.
A great summer to all of you :-)
Ulf