TP,
You may be better off with the X heads, world products windsor Jr. or AFS.
Info on the GT40P heads (w/flows):
http://www.stangpro.com/html/article...les/gt40p1.htm
Here is a good flow test, need a subcription but there is a lot of great info:
http://www.fordmuscle.com/archives/2...ds/index.shtml
The nostalgia seems a little soft to me, you might look at comp cams 31-414-3, 224I/224E/110O/0.500L for a great street cam.
How is the build coming along?