"There is/was a full size replica of a Spitfire (Viking Spitfire) in England somewhere, powered by a Jaguar engine, modified to about 7Litres, it was a wooden framed aircraft, and around half the weight of the real thing, it seems to have quite a good performance".
Ian – that was at RAF Hullavington, in Wiltshire. I ran an RAF MAA gliding w/e there, back in the '80s, and it was still under construction. It most certainly looked the part and, with nothing close to scale it, easy to see it as full size – it was, however 2/3 scale (as I recall). There may have been another, as you describe, but I haven't any knowledge of same.
rgds
Bill