Works with Rage Latest and STE brand SK Synchrometer Flow meters.
The default adapter seems appropriate for Weber carbs. It is too narrow / deep for Solex 40P11-4. You will hit the squirter nozzle and the synchrometer won’t sit flush.
I’d suggest a strip of painters tap around the joint to minimize leakage and to keep it from falling off.
Probably not as good a seal between adapter and carb as you would get with rubber, but I think it’s good enough.