Machined part reference material?

I always put a note that calls out the material.
For example-
Material: Aluminum bar 2" x 4" x 12' 2024 alloy.
I never show the overall (of the raw stock) because it usually doesn't matter how a fabricator gets to the final dimensions as long as the final part meets the print.

But you can always use derived parts,etc... You will need 2 models (like partRAW.ipt and partmachined.ipt) then derive that and add your machining steps.. Then just show both parts in the print.

I've had parts that get made as blanks then might have different secondary operations performed so I have 1 part number for the blank part then another part number for the part made from the blank.. And just call out in the notes that it should use partxxx for the material.

Having the 2 parts is a good idea but that means I have to have the part completely acurate before I derive the part correct? In other words if make any significant changes I'd have to derive the part again (I think).

Basically I have a machined casting so the casting would be one detail print and then the machining process would make the second detail print.

From what I gathered there isn't a way to show features the same way we'd use the representation in an assembly? And for that matter could I create an assembly and cut the part where needed and use the representations?

Derived parts are associative, so you can edit the original and derived will update. In some cases I derive the machined and then add back the machined material.
Less often I create the casting and then derive and machine (more like the real world operations, but you often don't know the casting dimensions until after the machined part is designed.
There is a bit more to it, the best way to communicate is with one of your actual parts. Attach the part if you can.

Oh, and I forgot the original question - you can show the casting as an Overlay view (I set the linetype for phantom for the material to be removed.)

Weldments allow you to add machining operations but you can't show them on the same view. You can however show different stages of preparation in different views.

I quite often sketch on the view to add some details of removed material. I don't go into much detail just show rough overall.