IMM Iron heads on that Mag 318

they claim good port speed for a 410ci, this means...too big for a 318 with 3.23. You need alot of cam to take advance of the port size. It "wont" work (well) with 3.23
If you have the money, you buy them, and a cam that fits 3.23, then ask them to epoxy the runner to get correct air speed for the camshaft and your engine volume:-)