ok fellas whats the best way to store heads that may not be used for a while. Do I coat the machined parts in oil to stop any corrosion and store in plastic bags.

i just spray with chain lube , auto trans fluid mix with a bit of kero .its all good

The brown paper that has been referred to previously that wraps OEM and after market parts is not plain brown paper although it looks identical ,it is a protective wrapping manufactured by a number of company's , one being Cortec ,the product used in this application is VPCI it is a wrapping that gives off a vapor which protects the parts from corrosion ,but the product would have a pre treatment that is designed to augment the wrapping.
Next time you get parts that have this protective product wrapped around them ,save the wrapping in a zip lock bag and use it when you want to store your parts if that method suits you,but bear in mind you will not fully reproduce the longevity of the original conditioning  . When i store anything i spray it with "Corrosion Block CF50" if its good enough for Rolls Royce to store jet engines its definitely good enough for my stuff.