Thanks for the comments everyone
I modified the Spiral I have to not only fit on the P4 this time, but it now has 5/8" OD hosebarbs. I will be using it for comparisons to my block.
I used 1/2" Lexan and just kept the O-ring in place for some testing and used the original screws for a quick fix. I am going to get it back to the owner (I swapped a twenty spot for it) with the AMD holes drilled out and use a full size gasket and heavier cap screws with washers. (The original top was cracked)
Here's a shot, has anyone ran it with larger barbs?