Old cast iron motosr and how to tell cast iron from steel ?

I'm new to the forum so bear with me.
I had a couple of engine blocks I tore down pulled the crankshafts out and rods and pistons because they are still usable.
Question I have is what do you do with the cylinder heads ?
Do you remove the valves and springs so you can get clean cast iron prices for the srap?
I have a cast iron pile I am putting together old rotors, engine blocks, and would like to get the clean cast iron price when I go to the scrap yard.
Another question, is there a way to tell cast iron from forged steel ?
I did try sparking and viewing the color of the sparks, but the sparks were orange in color on the steel and also the cast iron. Could not tell a difference, is there another way to distinguish between the two?
I'm hearing steel is 200.00 per ton.
And Cast Iron is 300.00 per ton.
Thanks in advance for your replies.

Check with your yard, but usually #1 Iron, Cast Iron and Motor prices (includes heads and blocks) are the same or very close - so close that unless I've got a couple tons of the higher valued stuff, it's not worth the hassle to keep separate. I often can just throw blocks (and heads), Cast and #1 together.

To tell Cast from Steel - Cast will break but not bend (hence the term "Cast"); Steel will bend before it breaks. Both will throw sparks.