well the stuff you're talking about will work against those who don't understand how terry block strings work, however here is a fair warning against those that do.
d.D, df+C into D crackshoot is not a true blocksting and even especially if they are not standing ( I know that's exactly what you want, but there is a benefit on the opponent's side too) I'm sure you are aware that some characters can down. B you before crackshoot is able to hit you, doing D version makes it much easier to see and execute, free combo for them.
Another disadvantage is if they block high, anything you stick out afterwards will get stuffed by their normals, unless you rising tackle. however against CMND grab characters you can't even do that to escape, free punish for them, your only option is to block, or eat a punish against cmnd grab characters.
like any game that involves another opponent, you try to test the opponent's knowledge and abuse what he doesn't know, however for those that do terry becomes a difficult character to use. Mr.KOF said, if I recall correctly, that terry's game play is too predictable and against opponents that understand him I tend to agree, the thing is only a handful of people really know but if your terry becomes dominant enough they will go out of their way to find out