GIve French diplomacy some years to work and they MIGHT get the Italians and Austrians interested in an alliance.
Maybe that borders ASB territory:
Say they can strike a deal - Austria is to cede some territory Italy wants (we all know what) in exchange for a large piece of Prussia (say Silesia).
If you delay the war long enough (late 70s) you might have the Russo- Turkish war be the spark of a larger war. England and France will be helping the OE and want to repeat the Crimean War - with BETTER logistics and better prepared

- OTL Prussia/Germany was neutral but TTL there is no Germany (just Prussia with a few southern states) - there is a chance that Bismarck is not as important as OTL, so the Prussian king is supporting the Russians this time (he sees what neutrality did to Austria last time

). THis might spark a French reaction and a French (but not UK) DOW on Prussia - with Italy and Austria following. Voila a large European war in the late 70s....