I think that’s a Ford Cosworth FVA engine, have seen a few 47’s converted to FVA in period pics - 16v head and a variety of engine capacities up to 1600cc. - The 1600 bottom end is basically a TC so it could be classed as a cylinder head swap.
The FVA was developed as “proof of concept” for the DFV.
It’s possible that they where also using the engine to enter different classes that required a smaller engine capacity.