Subject says it all, are Stargrave / Frostgrave heads compatible with Crooked Dice minis or would they require some modifications / green stuff to fit?
Sub questions, Crooked Dice minis do come with the heads apart from the bodies or are they single pieces?
Cheers!
Here's every scientist's favourite answer to this, "it depends".
As for the general style and workload issue, I suspect they will fit reasonably well with the traditionally-sculpted ones, whereas the 3d-sculpted Veingart models may look a bit off, as these are generally a bit slimmer and sleeker than putty-pushed ones. Still, I think it will strongly depend on the specific combination of head and figure. I have used separate Crooked Dice heads with other figures, both plastic, metal and scale figures, and it generally worked reasonably well.
As for the issue of separate heads, there are some figures, especially in the fantasy ranges, but also the Colony 87 pieces and the post apocalyptic stuff, which are generally integral and not separate. You should probably check, and it should be stated in their web shop entries if heads are separate and require assembly.