Battery Grounding

I am installing a second battery for winter as I am adding a plow to this truck. The block is quite rusted and flaky due to the amount of heating cooling cycles not giving me a good place to apply my ground cable. Alternatively I have a very clean place on the driver side head. As you may or may not know, the heads on this particular engine are made of aluminum. Can I mount this ground cable to the aluminum head or will it cause me problems internally by passing the current through it.
My first thought was passing current through the valve train as the heads rest on the head gaskets. Further though reminded me of all the bolts that contact the head holding it down being screwed into the block. The second thought made me feel better about this, but I thought I would inquire from a professional if I should and if there may be something I am overlooking (engine safety-wise).
Thank you in advance for your advice.