Well here is the answer it is a billet alum. .250" thick mount. It fits all 6-71 thru 16-71 roots blowers, includes grade 8 mounting hardware and has been anodized.
This will work with Enderle, Gorr, or most other fuel injection eight port or twelve port distribution blocks that use a 1/4" mounting bolt. Distribution block in picture is not included but can be purchased separate.