It depends on how picky you are regarding accuracy and which period your Zouaves are intended for (Crimean war ? Italian War ? Franco-Prussian war ?). The cut of the uniform was identical in both cases since the American version was a carbon copy of the French original, at least in those few regiments which retained the baggy Zouave trousers : most units in the ACW actually wore narrower chasseur-style trousers. Fortunately, the Perry plastics are based on the 5th NY, which copied the French style pretty faithfully.
The major differences would be :
a/ Canteens : the French army used square ones rather than the round type issued to U.S federal forces.
b/ Musket and bayonet : unless you have a particularly sharp eye, the musket will do for pre-1859 Zouaves. It won't pass muster for the Franco-Prussian war though, as the Chassepot looked significantly different. Also, the bayonet won't work from the late 1850's onward : by the time the Italian campaign started in 1859, French zouaves were issued with saber bayonets while the Turcos retained the traditional socket bayonet.
c/ Cartridge box and haversack : the former will be roughly O.K until the late 1860's, but the introduction of the Chassepot added an expense pouch on the waisbelt. The French haversack didn't have the strap on the flap, but this can easily be remedied with a hobby knife.
There are a few other nits you could pick, but these are the most immediately conspicuous differences.