Any NOS pump you buy is going to have a diaphragm that cannot tolerate
modern fuel, at least in the USA. I don't know if Europe is using
oxygenated fuels to meet air pollution rules or not, but if they are, you
need to replace all rubber parts in the fuel system with modern parts.
I agree with you ! Yes, in France we've two unleaded fuels, one is the
SP98 (around 93 US octane rate) which is very agressive with rubber and
the other is the SP95 (around 89-90 octane) which is less or no
harmful. Since 3 years i used the 98 and i switch to 95 2 months ago.
The car runs well with this lower octane gas but i've noticed that it
runs at little higher t° (seen at gauge). I'll decrease a little the
advance as someone told me.