Yep, this is the problem. I have different plates. You can see that mine have more squared lower corners, where yours are at a 45.
I found a set at Jegs, looks like I might use the gaskets for a 4160 secondary. This image is from Holley.
I found a set at Jegs, looks like I might use the gaskets for a 4160 secondary. This image is from Holley.















