Heads Explained

I have a mild 318 combo at the moment. It was a factory 2BBL engine and I now have an airgap with a 4bbl. The heads have 360 size valves , small amount of bowl work and the opening of the inlets was gasket matched to 360 gaskets and the airgap.

I will look for a casting number but I was wonderng what the chamber size would be and my best improvement for power on a budget.

I am looking at adding a 75 shot of Nitrous to the current set up and ideally want to build a 390 stroker at some stage. So any heads I buy now would have to work with that engine.
I live a fair way from a big city and drive the car a lot to go on runs etc with our club. Even the 390 I was looking at Hydraulic cam etc for reliability

I found these on the hughes site

http://www.hughesengines.com/Index/...el1=Q3lsaW5kZXIgSGVhZHMsIElyb24=&partid=25741

Anyone have any feedback on them or am I better off finding a 360 head and getting it done. Will I loose compression with the 360 head ?

Thanks in advance

Shaun