Let me know if you want some, happy to send a bunch as long as you like green powder coat, that's mostly what I've been doing lately. Bare lead is possible but the lubrication from the PC is attractive. I have all three sizing dies and normally size after PC. I also have Lee REAL 50 cal that I need to cast and size down to .510 if you have an interest in any of that. Assuming I get stuck with the mess of the Hammer, I'll still need ammo to put through it.
The bigger question would be choke or straight on the Bighorn, these may not work well going through a choke. But being 357 I would hope there is no choke present, being stuck with pellets would be a real shame. I'd also be happy to send some in any or all of those sizes, doesn't really amount to much work to size some into all three for testing.
If you want to single feed, I have a 125gr that I can send too, another Lee design that works well in my Bulldog. Pretty sure it will be too long to fit in the Bighorn. Lee lists this as .565 over all length (Lee 356-125-2R). these can be a little harder to get up to .358, even after powder coat, but I can give it a try.