I got my headers from Street Beast that was located in Florida. Street Beast has now gone out of business.
So I have taken several pictures in hopes to help others to create thier own headers.
The Headers are mounted using Stainless Steel 3/8 - 16 x 3/4 Hex Head Bolts. The Hex Head is 5/16.
Later the exhaust pipes will be mounted to the headers using the same bolts. You will need a total of 24 bolts.
The angle of the plate from headers to exhaust pipe from horizontal is 42 to 45 degrees.
From the head to the center of the plate is 16 1/4 inches.
Measured from the front of the head.
And from the back of the head.
It measures 17 1/8.
16 7/8 across the top.
16 1/4 through the middle to the top.
I hope this helps, if I can do more let me know.