Im building a set of GT40-P heads for a fairly stout 5.8L project that is underway. As always saving a buck in the name of performance is always a must. Ive seen several spring packages on e-bay but being new to the Ford performance world dont yet know the interchange as well as standard part specs. Anyone know the installed height for the stock valves as well as the stock spring diameter for these heads. What is the max diameter spring that will fit without opening up the pockets. Im running a .511 lift cam.