The above recommendations are good. I've used 4198 (both) and others. My favorite load is 30.0gr of #2400 under the RCBS .458" 300gr FNGC sized to .459" and gaschecked with a Hornady GasCheck . This gets about 1,600fps from my rifle. Accurate, flat shooting, and comfortable to shoot. 43.0gr of H4198 gets 1,900fps and is nearly as accurate but not nearly as comfortable to shoot.
I really liked Varget (about the only thing I really liked it in) my .45/70 under a Lee .459" 405gr Hollow Base cast bullet with a compressed load of ~55.0gr of Varget. But, I can't say it was remarkably different than IMR4064.
Lubed with SPG and sized to .459", I got 1,950fps from my 18.5" GuideGun. However, recoil is fierce. Accuracy was ~2moa @ 100yd 3-shots.
Ever shot a MkX Mauser Whitworth in .458magnum? Recoil was a tad more than a full case of H4895 under a 510gr Hornady Soft Point @ 2,050fps from the Whitworth. A sweet shooting gun,actually. Owner took an elephant and cape buffalo with it in 1999......(local physician-aquaintance who knew I had a chronograph...).
I did mean FIERCE recoil......from the "little" BIG Marlin.........