ddouglas, all the naca reports are on nasa's web site downloadable in PDF form for free here:
http://ntrs.nasa.gov/ . They did an incredible amount of work with piston engines prior to the advent of the gas turbines. Report number 768 deals with Hemi engines and 655 pentroofs and some others. Keep in mind these two reports only deal with detonation issues as they were trying to extract every last bit of power out of available engines and fuel. There are other reports dealing with just about any aspect on engine design you can think of. While it's old information it was compiled by the sharpest people around with a budget to do about anything. For a simple hot rodder like me they are an invaluable resource.
They are still comming out with reports but they rarely have anything to do with piston engines as turbines and rockets are all nasa cares about now.
I am glad you are here. We need all the engineer we can get.