The 2004 Ford Racing Performance Parts catalog has a diagram and the equation you are looking for. Look on page #148 of the catalog.

http://www.fordracingparts.com/parts...atalog2004.asp
There may be other places to find this formula, this is just the one I'm familiar with.

BTW, that is the "standard" formula that uses the volume above the piston at BDC.

As I understand it, if you want to compute the DCR, you will still have to determine the total volume above the piston at the closing point of the intake valve.