Yep, well made, and a good idea if you're rebuilding a head on any bike, and if you stamp the base plate with "Inlet 1-4" and "Exhaust 1-4" you can work out which one goes where when you re-assemble it.
I'd make it so that you could store the appropriate valve and keepers etc with each spring, if I was gonna go that far, particularly if those parts were gonna be out for a long time. Cheers, Terry.