That will work for a plinker. FortuneCookie45LC used a soft-cast, PC painted and lubed 340-grainer sized to .458" as a barely supersonic plinker from his .458 WM, using 16 grains of Unique and no filler. The Berry's plated bullet should work as well or better.
AA-5744 might do even better (no filler needed), and don't forget to try H4198 and H4895 with filler. Speaking of H4895, here is an abbreviated re-run of "No Name Handloader's" work:
H4895 can be used for just about anything good, bad or ugly in the .458 WinMag.
Ron aka "Rip" for Riflecrank Internationale Permanente NRA Life Benefactor and Beneficiary .458 Winchester Magnum, Magnanimous in Victory THE WALKING DEAD does so remind me of Democrap voters. Donkeypox.