Off the subject question, but I have to agree with Honn. If that head is coming off for any reason (studs, o-ringed, thicker gasket) slip a new cam in there.
You have been running dd3's for several years now with that 40, so EDM 4's or 5's should still keep you in the safe zone with Twins, providing they can light up fast enough, or keep the boost up under load (read - pulling up hill).