Help with my first engine build (5.9 Magnum)

Get a set of rod and main bearings also. And check the cam bearings. The magnums had detonation issues because of the valley plate on the stock efi intake manifolds and ate oil which caused them to detonate. 3 of the 7 I’ve disassembled also needed cam bearings. Your keepers just need to match your new springs and retainers. Buy accordingly. The stock magnum lifters will be absolutely fine with your cam and intended use, no reason to spend money on new anything. Clean and reuse the stock ones.