EQ Magnum head max lift?

I never measured my EQ heads for max lift, but if I understand correctly the basic guide height is very close to stock Chrysler Magnum castings, so that .544" lift is getting close to max lift dictated by the retainer to guide clearance. Your safest option is to measure your heads since you have one apart anyway. Leave the spring out or use a light checking spring if you have one. Make sure a valve stem seal is in place. Then just measure how much the valve moves from open and touching the seal lightly to fully closed. Now subtract a safe amount for retainer to guide clearance and that will be your available max valve lift of the head. You'll need to double check the actual valve spring for coil bind while assembled too, but this is how you can easily get the real numbers for your heads and valve parts.
Hopefully that helps, because it feels like I may have been rambling on.