I remember a kit car manufacturer that I spoke to years ago who was building Ford cortina based kits. He Had contacted Fords about the accuracy of the diagonal measurement he had between shock absorber mountings which were 3/8" out and Fords said that was miles better than a MK2 cortina, so our donors probably vary by the same if not more.
These Sammios will look fine and no admirer is going to start running a tape measure over them.
I think you guys are doing a fantastic job, great inspiration for us novices starting out.
Len.