Annette,
Wish I could give you some woodworking tips but perhaps this link might help if your up to another attempt down the road:
https://sites.google.com/site/oldiro...adapter-plates
I think the hinge pins would add a degree of difficulty that is not essential. If I was in your boat I'd make a quick and easy 3/4" top, perhaps reinforced in spots with 1x while searching for a proper Davis cabinet depending on how well you like the machine.
Jon