[Tim Brewer]

I believe those are the P-51 heads. I would just give Jon a call and talk to him about them. I think they are supposed to be good for a 50 hp increase. The P-51 heads are configured differently, but the big question is... what would be the difference in having your heads profesionally ported vs the P-51? It would be much cheaper to port your existing heads than purchasing new ones. I have been thinking of this very same thing. I know Keith Craft has a CNC port program for the Cobra jet head, I'd give him a call as well.
Good luck and keep me posted,
Tim