Sadly, I don't think your modified adapter is going to work with this engine stand. I am truly amazed at how much Harbor Freight has stepped up their game when it comes to this engine stand.
The plate is a full 3/4" and the round mounting for it is exactly as follows:
1) Inner Diameter of the round OUTSIDE mount is 3-1/16"
2) Outer Diameter of the round that goes inside is 2-15/16"
Both have 3/16" walls.
http://devestechnet.com/DSC01423.jpghttp://devestechnet.com/DSC01424.jpghttp://devestechnet.com/DSC01425.jpghttp://devestechnet.com/DSC01426.jpghttp://devestechnet.com/DSC01427.jpghttp://devestechnet.com/DSC01428.jpghttp://devestechnet.com/DSC01429.jpghttp://devestechnet.com/DSC01430.jpghttp://devestechnet.com/DSC01431.jpgThis is miles better than the ones that were out there a few years ago. The center of gravity is shifted with the mount considerably inside the wheel base, and there is angle brackets on both sides of it. Way more stout than the other two I have here that I repurposed. Then you can fold it up just like the engine crane when you store it. Very cool!
