360 Magnum engine how to tell where is front of piston ?

Disassembled my 360 Magnum engine and numbered each piston/rod assembly.
These are the stock pistons, I want to reinstall them, I know I need to orient the piston to the front of the engine, but I cannot see a mark on the piston to do so. No notch that I can see on the piston. Anyone know how to make sure I don't get them backwards ?