The images were for the size comparison ,14 .5 inches ,the old rover is basically the same size the later 21 inch rover has a slightly smaller plate but may still work.
Yes I was thinking you would need to machine the centre out and machine a cap up then weld it to the plate.
Old Rovers are anywhere from Free to $20. for a cheap one.The Rover plate looks about the same dish or hollow as the Victa.
The problem may be how big a Lathe you are using to fit the blade plate in.
