Plenty of the Against the Slave Lords monsters are specific humanoids, similar to the ones at the back of the MM but with class features blended in. There's about 30 of them. So while you could homebrew them, it's a lot easier if the monsters hold up with a couple of minor tweaks.
I posted a conversion of Legacy of the Crystal Shard here. As I was converting monsters that did not have a monster manual equivalent, I noticed that you could do a good enough job by multiplying the hit point values by 2.5 and leaving it at that.
