This one was designed more as a Snow Plow
... but a good fabricator should be able modify it for a center mount as well as modify the blade itself to fit better. A little creativity could make it hydraulically actuated as well so you could angle it in multiple planes. It is rudimentary but does give the basics.
To have a good look at what IH went through in it's development of the Cub-54A Grading and Leveling Blade then the CBI-1A Revision 12
- Cub Leveling and Grader Blade
If I was to build a blade setup from scratch for the Cub I would be using IH's version as the basic building block, fix the shortcomings and make it fully hydraulic. I certainly would not beef it up too much unless you have multiple attachment points - mounting pads/drawbar and torque tube. Be careful with the torque tube though, ugly stuff can happen in a heartbeat. Make sure you have a spring trip just in case
Dan: Are you prescient????