The screw holes are in a different location if I remember correctly. Also, the rear edge of the neck pickup will be located closer to the bridge and will most likely require routing to fit, unless it has a large enough route in the neck position (the last one i looked at did not appear to). You could ask EB CS if they have any old hsh assemblies for a silo special floating around. Chandler should have them, too.
24 fret vs 22 fret, the HSH Silo pickguard will be too short for a Silo Special. As Pete said, the Silo Special is routed for HSS, so the body would have to be cut for a neck humbucker and you'd have to get a Silo Special pickguard for HSH (or modify an existing one).