Oil consumption and ticking after cam swap?

how? coil bind I can understand but how about retainer to valve seal? That is a pretty fixed dimension. IE, how much valve stem is showing under retainer? Is it gross lift inches plus some clearance? Im not a magnum guy but if someone can tell us the max lift cam they are running ona stock magnum head, then we could determine what the max lift available to stock valves and guides is.

I assumed the shape of the bottom side of the retainer is different.