Is it possible to make custom properties into material selections on a BOM?

What I have is a valve drawing, that covers multiple sizes that all look close enough for most people on paper to make them happy. What I would like to be able to do is somehow set up a set of custom properties for the assembly that allow me to change material types at the drawing level.

I know that everything is associative, and that I can open the model, change my material types there, then open the drawing and the BOM is updated, I just want to, for lack of a better term, lock down the model, and only have the drawing change.  For example, a standard body type may be Cast Iron, but I need to do one in Ductile Iron. I would change the material on the drawing, update the job name, save to pdf and be done.

If needs be, I can upload some examples, and I have even crazier questions beyond this that my reseler's support got stumped by. But I thought I would start off simple.

Thanks in advance for any assistance and advice,

Phillip Auten

SolidworksBill Of Materials