A very good book on the World War II navies, comparing such things as radar, ordnance, aircraft, etc is from Vincent P. O'Hara
On Seas Contested: The Seven Great Navies of the Second World War. I would recommend it, and also note he has a similar volume on the navies of World War I.
Italy for decades was countering France with a smaller, faster fleet. This was still the case in World War 2, though the Italian naval expansion was bringing things closer. Always cash strapped thanks to the Fascist handling of the economy, the RM abandoned night fighting training in the interwar period because of finances. However, they had the first iteration of what would become the Gufo (owl) radar in 1936-37. The program was historically put on hold in 1941 due to finances, but could well continue in a war just against France. We might see operational deployment in 1941-early 1942 with full funding.
For a Jutland style engagement, I would say it depends on when it occurs, as well as the larger geopolitical situation.
Geopolitically, where is the World War at? Does France have a commitment in the Atlantic countering Germany? If so, how is the fleet divided between the Atlantic and the Mediterranean? Or is this just a Mediterranean War in the World War 2 era?
In 1940, both fleets are still building up. The Italians will gain the advantage that year, with both
Veneto and
Littorio completing, as well as the second pair of rebuilds. If something occurs in 1943, the MN should have
Richelieu, Jean Bart possibly
Joffre in the OOB. I would expect the French to be fielding American planes, Douglas DB-7s (A-20), Glenn Martin 167 (A-22, Maryland in RAF service) on land, Curtiss SBC Helldiver (the biplane), Vought V-156F (SB2U Vindicator) and probably Brewster 339 (Buffalo) and Grumman G-36A (Wildcat minus the supercharger) at sea. I would expect the RA to be fielding the historical Italian types, and I have my doubts as to whether they would look to Germany for a dive bomber, or even adopt the tactic unless experience would dictate it. If
Aquila is completed in time for action, I would expect her to have the Reggiane Re 2000 Falco. The Falco was a difficult plane to maintain and fly, so that might impact
Aquila's effectiveness as a carrier.
France's fear in most of the interwar period for a war with Italy was the RM would cut France from her North African colonies with growing power of the RM's heavy cruiser fleet. Rene Greger points out in his
battleship book,
Dunquerque was as much a reaction to the growing Italian cruiser fleet as to the panzarshciffe. Certainly, any ship that can kill a panzarshciffe can kill a heavy cruiser. And while both
Dunquerque and
Strasbourg are good ships (the latter has better armor and flag facilities), if matched against all four of the Italian rebuilds, I would expect the
N-squared law to be in effect.
The French concern with the heavy cruisers was because the RM dreadnoughts were just that; useless, 21 knot, 12in armed dreadnoughts, in and out of reserve for training roles and near useless in modern warfare. The rebuild took those ships and turned them into modern combatants that even most capital ships could not ignore. More importantly, the rebuilds occupied drydocks, not valuable building slips.
The Italian heavy cruisers were essentially two three-ship units of homogeneous ships. The
Zaras were heavily armored, while the
Trentos and
Bolzano were more lightly armored and faster. The MN ships were more of a hodgepodge, even within a class;
Dupliex had over 500 tons more armor than the name-ship of her class,
Suffren. Even if France is not overrun, I have my doubts as to whether the
St. Louis class (14,000 ton, 9 x 8in CAs) could be built and commissioned to make a difference in the conflict.
Without a number of the Capitani Romani class CLs to handle the MN
contretorpilleurs, I would expect the Condottieri light cruisers to do that work.
As has been pointed out, RM light forces were handled with great élan, (See Mimbelli in
Lupo and Fulgosi in
Saggittario for examples) and an Italian effort against Toulon or Mers-el-Kabir such as Durand de la Penne executed in Alexandria would not surprise me, and could tip the balance of naval power.
Overall, Italy's fundamental problem is her commerce is controlled by the RN. Without a global war, does the UK shut off the Suez and (less importantly) Gibraltar to Italian commerce with"contraband'? With a war, as historically, she'll have to depend on Germany for oil and Germany will have her own issues. The longer the war, the more I would expect French industry and access to world trade to make an impact.
So to sum up my somewhat jumbled thoughts, I would expect a shorter war to be better for the RM, a longer war better for the MN.
Just been reading the Osprey book on Italian Cruisers . Apparently their guns were too close together that caused issues .
Dunquerque and
Strasbourg suffered dispersion from barrel proximity as well. Delay coils were the solution. I could see the Italians introducing delay coils on the 8in cruiser turrets if they find this a problem in combat.
Regards all,