hello kid, I just got done reading your whole thread, didnt' mean to start another thread about almost the same thing, but i thought mine was slightly different. To answer your question. I have a 8 gallon cell running through a high flo summit filter and then through the factory lines up to the pump which was a 120gph mechanical.
This is the /6 factory lines which i thought would be way too small but i have a fellow racer running a low 12 360 scamp with the same lines on a 850 holley. And it never had a problem until i dropped it down a gear as explained above. But as I'm typing and thinking (quite a feat i tell you) I did jet up quite a bit and that could explain why it's doing it now and not before under the smaller jets. but in the same breath I ran one other pass with no problems at all. Don't get me wrong I think i'll be installing some 1/2 line real soon