FreakyFast, definetly go witht he GT40P's. You can actually use regular headers with the P heads but you will need a 90* plug boot on plug 3 and 7. Also to remove the sparkplugs you will need to take a spark plug socket and shave about 3/4 of an inch from the spark plug socket, bench grinder works wonders. Then you can use this socket to change your plugs, if you were to use a regular socket, you would be S-O-L and it would hit the headers and be impossible to take them out. Anyway, the P's are more effecient than the standard GT40's, compression wise. If the money is available I would mill them .030 replace the valves to a 1.94 in/ 1.54ex valve get a valve job done, replace the springs and the locks and retainers. I can hook you up with someone who can fuly race port them, and also the same person can hook you up with a custom grind cam, not my cam builder but this guys cam and portwork are very superior. Were talking some cash on this job, but you will have a head that will outflow just about any stage 2 port job on an aluminum head.