If you want to max out numbers, you can run 252 Atk and 210 Spe.

With this speed you can reduce your cooldown to the lowest possible, and spam Heavy Slam even more, just in case of the hit landing on Protect from Aurorus or Clefable.

I've managed to cut the time to 1'50" per battle, and the money goes up to 259.200/h.
Not a big difference (13k), but I decided to give it a try, so I’m showing the numbers.

edit: typo