Clyde, if you are a fan of Cape Feare, and I agree that it's one of the best episodes ever, then I think you will find much to enjoy.
Almost every scene and joke is recounted in the play, but two of my favorite lines from the episode sadly didn't make the cut:
When Grampa says that they should call Matlock to figure out who is sending Bart the letters and Bart says, "Grampa, Matlock's not real," to which he replies, "Neither are my teeth, but I can still eat corn on the cob is someone cuts it off and mushes it into a fine paste. Now that's good eatin'!"
When Selma is on the stand she claims Sideshow Bob tried to kill her. The lawyer asks the courtroom, "How many people in this court are thinking of killing her right now?" People slowly start to raise their hands. "Be honest," he encourages and all the hands go up including a priest and Patty who says, "What? She's always leaving the toilet seat up!"
Marie: Don't be in such a hurry about that pretty little chippy in Frisco.
Tony: Eh, she's a no chip!