1. IME, pressures go UP with lead bullets, compared to jacketed. Winchester's loading data from the 1980s when they had more powders tends to agree. Pressures were published, and equal-weight lead bullets almost always took less powder, at same or even higher pressures.
2. WW-296 works great with Oregon Trail 125-gr TCs in two .357s I've shot them in. 1400 fps and decent accuracy. YMMV and all that.
3. I tried working up with now-discontinued WAP (don't remember what Ramshot or whatever powder it is now--I really liked its low-flash tendencies) just before there was published .357 data on it, and it was kind of a flop. Pressures went bad before I could get very close to full-power loads. Accuracy was so-so.
4. Herco and Unique seem interchangeable in performance with 146-grain and heavier bullets, BUT with differing charge weights. For my favorites, 125-gr bullets cast and Hornady XTPs, Herco seemed to pressure spike about 75-100 fps slower than Unique.
Finally, with my 125-gr loads (I know you're asking about 158s), there really is a noticeable recoil difference with comparable velocities, between the 19-20 grain WW-296 loads and the other loads using more like 10 grains of powder. Total mass of recoil ejecta, my friends. It's a physics thing.
ETA: Power Pistol works pretty good, gets close to max velocities with less powder at least with 125s, but it still flashes pretty bright like WW-296. I really considered fabricating a flash hider, but I was not shooting an L-frame at the time with that convenient lug to screw it onto.