Alright, let's say Italy is much better behaved. Italy stays out of Ethiopia, accepts France and Britain's offer of colonies and shares in Suez in exchange for neutrality in 1940, and Italy honors the agreement even when France falls. Italy stays out of Greece and at most gets Albania and a border adjustment (big or small) with Yugoslavia during the war. Vichy France joins the Axis for some reason at some point. Things otherwise play out fairly similar with the US, Britain, Germany, USSR, and Japan.
If Italy offered to join the Allies, would the allies be willing to allow Italy to take any territory from France proper? If not, what conditions would be required for the Allies to consider it? Is so, how much would realistically be offered or accepted by the Allies if taken?