Deciding on heads..please help

[dragstang86]

Im trying to decide what heads to buy. Right now i have gt-40P heads on it. I was thinking about going with the gt-40X heads. How much of a gain do you think ill see? The ford racing catalogs say a 40hp gain for the aluminum gt-40 and a 65hp gain for the gt-40X but doesnt say about the gt-40P's. Im thinking about a 45hp gain? I can get these heads for 1090.00 through my work completely assembled. Is that a good price? Should i go with the 64cc or the 58cc? Or should i go with different heads?

thanks for the help,
bryan

c-4 tranny 3500 stall
306
gt-40p
cobra intake - ported lower
E-cam
70mm throttle body
roller rockers
373's
and all the other bolt ons and stuff