Here are some tips for using the CAM Lathe Simulation.

OneCNCXR3 Lathe CAD/CAM had a function where you can simulate the machined part from a model of the stock rather than a standard billet.

This applies equally to a casting or forging or a part already machined in another process.

Here are some tips on using the lathe Rest function.
This function provides simulation for your machine to assist in the ability to prove the machining before it is run on the CNC machine.