Finding a set of air vanes with the associated linkage bar, thermostat and thermostat actuator rod is the hard part. Once you get them delivered we can walk you through the installation and adjustment to make them work smoothly. The newer spring-style thermostat doesn’t look like the older, bellows style, but from what I’ve heard they work just as well. Don’t forget to check local salvage yards to see if you could find a whole fan shroud with the vanes intact. You have the older, “36 hp” style fan shroud. There is a newer version with a bigger fan, but it is flat across the top, rather than rounded like yours. For that, you can fit a bigger oil cooler and bigger fan and it’ll cool better - A must for engines 1,915cc and larger.
The German hardware to install them was slotted 6mm screws. Unless you wish to grow up as a sainted Purist, I would suggest going to a local hardware store and get a box of 6mm X 1.0 pitch X 12mm long (1/2”) Phillips Pan-Head screws and flat washers to fit. Those screws come in handy for a lot of stuff on these engines and a box of them is cheap - washers, too. Don’t forget some metric lock washers, just in case, too.