Paris will go overweight at high levels with the level 71 2 x 13.4" on all six R mounts.
Lyon and Normandie can fit the level 81 4 x 13" (Strasbourg guns) with one bind and severe
displacement issues. Don't bother.
For an at-level Paris and Lorraine, the BC II engine will give you a lower base speed but
a better overheat speed due to an immensely stupid overheat ratio for the CA I engine. In
general, you'll probably just have to buy them both to see how they will work with your
current engineer setup.
11/20/2010 Edit:
I now cannot recommend the CA I engine for the Paris or Lorraine until (very likely)
you're well into Alsace or you nuke kickass'd your engineers very early. I put five level
103's on the Lorraine, unboosted with 90-100 vets on each, and the CA I engine was running
25/39. The BC II capped 24/40 well before that.