I have a 67 Ford F-100 pickup with a rebuilt 352 with only 600 miles on it. When I had it rebuilt they used a 270H comp cam, new eldebrock 4 Barrel intake, headers, and I recently intalled the powerjection III EFI. I am looking for more performance and would like to know if and how much performance gains I would get by having the heads ported. It runs great compared to what it did prior to the rebuild, I would like to get as much as possible without chaning it over to a 390. Any help is appreciated.