How about the ZDZ 60 for the 31%?
One thing that matters with petrol is the fuel you use, USA has some extra additives in their fuel so they tend to get about an extra 200 rpm, us Brits have to put up with the low lead, low pollution petrol.
Foof, it is actually probably the other way round. European fuel has a higher octane level, our standard is 95, in the US it is 89 (i think), so if anything, they would run slightly better here.