I used herco last about '95-'96, so the memory isn't so good.
I found herco works best with 170 grain bullets, so I have no data for you as I didn't find anything that was acceptable.
For accuracy with 210 grain bullets, I'd recommend 2400. The 17.5 grain load is VERY accurate, and will prolly be about the middle of what you could expect as far as recoil. As usual, the books are wrong on velocity, it's at least 100 lower than what the books say.
For the same accuracy, and a bit more OOMPH!, try H110 with a magnum primer.
With the load I used I use 3 pounds of powder, and don't have 1000 rounds made, so you go through some powder, but console yourself with the fact that you're saving a poopload of money by not buying factory ammo.
Remember, as always, do NOT reduce H110 below listed minimums, it gets a little squirrely.
2400 is an excellent powder for .41 magnum.
I haven't found a fast powder that groups acceptable in the 'middle magnum', it likes slow powders.
Your best bet to use up that herco is to buy some 170 grain bullets.
I seem to remember very good accuracy from sierra 170, but they weren't cheap, even back then.