Moparhead,
What has it cost you to put together complete heads? I've been watching those auctions off and on, and the guy seems to have a line on quite a few pairs at that price. I'm assuming (going from faded memory) that the Mag's use specific valve springs... locks & retainers for sure. Are the Mag RT's OK with lifts over 0.510" without any work to the spring seat area?
FWIW, these heads appear to ROCK on my Desktop Dyno 340. I thought it was pretty healthy for a low-compression engine (8.5:1, Crane HMV272 cam, 2.02/1.60 valves, pocket-ported heads similar to Steve D's in an old MM article). That configuration gives 348 HP @ 5500, 380 lb-ft @ 4000. Using W8's flow numbers, the as-cast heads give 377 HP @ 5500, 390 lb-ft @ 4000 (392 @ 4500), and the ported heads give 390 HP @ 6000, and 394 lb-ft @ 4000 (397 @ 4500). Between the flow, the bigger lift numbers, and the extra half-point of compression, that's a healthy 29 HP and 12 lb-ft bolt-on gain. Plus, it will let me bolt on my Magnum M1 EFI manifold without tweaking the bolt holes... Hmmm...
Clair