LA w/ stock valve spring magnum heads - maximum lift

If your changing valve springs you may or may not have to change the retainers. Locks (keepers) you can reuse but I'd suggest replacing them. Cheap insurance from a dropped valve just to save a buck. Factory stuff isn't quite as good as aftermarket. They will most likely be fine however with the spring pressures you require. Most times with smaller cams, the springs are designed to be used with factory retainers.
If it's a single with a dampner or a dual with dampner you should need to change the retainers. I think but not 100% that the mag heads were behive springs?