I started a thread on Cloudy Nights for a group build of an 8 inch F/7 Chief. I have had a custom lens make to mate with a Newport Optics COTS lens so that all the optics for this design can be bought and assembled into an unobstructed telescope. The 8 inch F/7 is a standard primary listed on Discovery’s web site. The concave corrector I am having made, the convex corrector is a Newport optics KPX205 lens and is listed for $75. Then it uses a 2 inch secondary mirror and a standard 2.14 inch mirror will work fine from a number of suppliers. Below is the optical prescription in Zemax for the 90 degree layout although other layout are possible
Here is a closeup of the correctors with coordinates taken from the Zemax layout.
Here is a link to CAD files and Zemax files.