1966 Corvette neg battery cable
 

I have a 1966 Corvette with a zz502 and noticed that the neg battery cable is attached to the engine at the back of the passenger side aluminum cylinder head. Is it OK there or should it be moved to the block/bellhousing? I plan to upgrade the radio in the near future. Also, where and how many ground straps should there be for the body and engine? I want to minimize radio noise as much as possible.