Probably work as long as it's a current and not a voltage output. Looks like the impedance is too low for a voltage output.
If it was me, I'd just buy an SSR that takes an analog input and phase-fires accordingly, so long as you can lose the zero cross (I think they still turn ON at zero cross and turn OFF at the point determined by the signal). I've used Crydom pretty much exclusively for SSRs, and they at least used to have that.