LA 318 w/ Magnum Heads What Pushrods

You can NOT and should NOT order pushrods based simply on what parts are on the engine. There are too many variables to just guess. Like cylinder head machining, block decking, head gasket thickness, etc. The correct way to do it is mock up the engine, buy a length checking pushrod and measure it. If you get lucky there will be an off the shelf pushrod in the correct length and you can order those. But save yourself the headache and do it right one time.
Solid advice. I'm going to go this way. Probably measure and order from Smith Bros.