Simon, I have the Adaptor plate on the shelf here in UK. Ford small block to Renault. Though the Renault 21 bellhousing is not the correct one. You will need to use the V6 Renault bellhousing. This is because when the tooling for the Reanult gearbox was made, it was using the Renault V6 30tx. When the Renault 21 (4 cyl 2.0 turbo) came out, GTD evaluated the gearbox and found it to have all the right gears and the diff to make a good box to use in the future. The bellhousing on the 21 is smaller than the V6 hence it was not suitable. If you have a 21 box, try find a v6 bellhousing. Or if your stuck call me or e mail. adaptor plate kit £195 stock.
All the very best
Mark Sibley