The answer is: the same. Higher grade fuel alone doesn't yield higher power outputs, but it allows for higher manifold pressure or compression ratio, which increase output; only if these latter are increase (and the engine can stand the increased load mechanically) will power increase. But its a very interesting find, did the French produce the 213 post war, too? I did not know!
IIRC the Jumo 213A had two versions, one with lower and one with higher compression ratio, for low grade B-4 and high grade C-3 respectively.