I'll cut to the chase, I have easy access to food grade CaCl2 and MgSO4, however I need food grade CaSO4 and it's virtually impossible to find in my side of the world unless you are buying like 100s of kilos.
How bad of an idea is it to dissolve CaCl2 and MgSO4 in water and crash out the CaSO4? The only unwanted product I can think about is MgCl2 which is also very soluble in water. I think after a couple washes I'd be left with only CaSO4.