Interesting question!!! I think most WWII era ammo was 115gr ammo, loaded about 1150-1200 fps out of a 4" barrel (pretty similar to what is available today). Probably there were some slightly hotter loads for the submachine guns, but I don't know the specs.
Please correct me if I'm wrong: the canadians loaded their 115gr ammo at 1250 fps out of their High Powers (bordering today's +P loads), and probably that was their only 9x19 load. The british 115gr service load produced 1280 fps out of the 6.6" sten barrel, and the german 115gr load produced 1300 fps out of the 9.9" MP40 barrel.