First you have to start with the 428 v.s. the 428 CJ. The CJ block differs from the plain 428 due to the additional webs cast into the main bearing saddles.
The SCJ block is the same as a CJ.
The differences for the SCJ were:
1) The beefer 427 "LeMans" connecting rods.
2) Cast iron PI (Police Interceptor) intake manifold.
3) An
oil cooler
That's basically it. Add additional choices for steeper rear end gearing and you had what Ford refered to as the "Drag Pack" option.
Oh, and there were "CJ" and "SCJ" 429's but this is the FE forum. not the 385 series forum.