Wigsplitter, you wrote, "One of you Magnum head guys should pm me about some brand new .600 lift springs I've got for sale."
Magnum heads have stupidly designed valve guide bosses that stick up out of the head far enough that if you try to open a valve more than .530", or so, the retainer runs into the boss and won't allow any farther opening than that. (.530")
In view of that fact, of what use would a .600"-lift valve spring be?
In order to use it, to take advantage of its capabilities, the heads would need to be removed and re-machined to allow the valve to open .600"+ to prevent the interference.
Am I missing something here?????????