It depends on what you are using the gun for, but if it were me I would leave it as a .45 ACP. Ammo is cheaper (about the same as .38 special in cost) and stopping power is signifigantly greater than .357 magnum.
There would be 0 benefits in going to the .357 magnum, you already have the more effective chambering and cost to feed the beast will be the same or lower. Plus reloading with moon clips is an awesome way to keep your revolver running. JMHO.
YMMV.