67 Barracuda Big Block K frame keep it or change it ??

Not to hijack, I am looking for clarification.

This is the first I have heard of the QA1 unit being weak and/or flimsy. Can you expound on this please? I have the QA1 K member and suspension pencilled out for my build.
I read in online reviews from customers, and do not like the overall construction to support the big block, also using a floor jack frequently to lift it up, is why I changed my mind..