With the Briareos lid, I primed the mold first with sandable primer, then layed in the shell-shock, it is best to lay in the fiberglass while the shellshock is still green, but it'll still bond even if the shell-shock is cured. I mixed polyester resin and cabosil filler and smeared in a paste coat, then added two layers of fiberglass. The shell-shock is brushable, but you have to stay on it til gets firm or it will pool in the low spots.
You can't get materials shipped in reasonably?
Smooth cast will delaminate if you let it fully cure between layers.
Russell