If You load a hot load with a fast powder like Bullseye and cast bullets, the bullets will tend to tumble 3.5 is a .38 special load 4.5 is .38+p.
My LEE Manual shows 5.8-6.5 for a 158gr cast SWC for .357 mag, that should be a safe load for the 140gr bullet but it might lead the barrel pretty badly.
Bullseye is really too fast for .357 mag. perfect for .38 Spl, though. This powder is so fast that you'll go over max safe pressure, before ever reaching true .357 mag velocity. With cast bullets, .357 mag loads are problematic, at best. Once you push a lead bullet that fast, with mag pressures, leading quickly becomes a big issue.
For actual 357 mag loads, you'd be better off with 2400 or even Unique.....with jacketed or plated bullets. Bullseye will work fine, in 357 mag cases, for 38 Spl loads.....and 38 Spl +P, as well. I don't recommend you try cast bullets at magnum velocities with Bullseye, though.....not at all.