To expand on what jinx said, not all pastels at 1200g look like this:
We were told she was a lemon pastel when we bought her but that doesn't really hold much weight because she was bought third hand. But one things for sure, she is super yellow still.
When selecting breeding stock, you want to select the best examples you can find. I've seen some real stunning pastels that weren't from any line as far as I could tell. A lot if people like the citrus line, but again you can have some sub par examples there as well.
Even selecting normals that you pair can affect the babies colour and pattern. IMHO dark normals should be paired to dark morphs and vice versa.
So not all super pastels are created equal. You can't really say that mixing 2 lines of pastel will make an amazing super. The best chance to "predict" an amazing super is to see the parents. If both are head turners then the babies have a good chance to inherit those qualities.