Just thought I'd throw my 10 cents worth in on this one too. In addition to the cam, water pump, clutch to be changed and con rods and pistons to be rotated 180 degrees, the crank also has to be changed to use the early R4 800 series motor in a Dauphine. The drillings in the R4 crank are for the reversed direction of travel. As you virtually have to source a Dauphine motor for all those bits it sounds a lot easier just to swap the motors if indeed one could be sourced :-).
Also the 1108cc five bearing motor won't just bolt up to the Dauphine gearbox, you will need to install the R8/10 gearbox/axle setup too.