Here’s what I have been doing:
Cold Ones - I use these guys as my Raptadon Chargers (the melee version) while building my actual raptadons as hunters (the ranged version). They are the correct base size, correct number of models per unit and have the full command options. Even the physical size of the model lines up pretty well. I have most of my saurus knights armed with spears, which also lines up well with the raptadon chargers lance weapon. The only little bit of weirdness is them having the skink keyword instead of sarus, which does matter to Fangs of Sotek and Koatl’s Claw constellations, but it’s easy to remember. And I havent had a single opponent yet mind the swap.
Sunblood - He’s easily used as an Oldblood on Foot, which I have a lot of fun with in the new book. Just make sure he’s on the correct 32 mm base for an oldblood, not the larger 40 mm base the Sunblood came with.
Skink Priest (not Starpriest or Starseer) - I just use these guys as Starpriests. They work just fine, and gives a wider variety of different Starpriest models to field. And in the new book, with cosmic power points, I like running multiple Starpriests in a Fangs of Sotek list. When I run Fangs of Sotek, thematically I like run skink wizards instead of Kroak or Slann too much, and all those priests give me more variety to do that. Also helps me keep track of who has what spell when I have very unique models between the Starpriests.
Razordon - This one is a tough one. You could certainly rebase the razordon model on the correct base of 90 mm x 52 mm oval base for a Spawn of Chotec. I dont think anyone would bat an eye at the difference in models.
I think all those options are completely acceptable to get these older minis still in your game.
