excuse me if I'm totally off , I too am building a 71 hemi cuda, just got my motor yesterday. I've been talked w/ Ben @ Shakerhood.com today about K members, he advised if using a Shumaker engine conversion mount on a 340 K frame, the engine sits 1.5" lower than if K member is modified properly for Hemi.
I don't know if this is what you all are talking about, but if it is, maybe that's the problem.
Cudaaah