Tom,
You appear to be missing the crankshaft pinion (gear), the inlet camshaft and also the magneto drive gear. If you are a member of the LDMCC then you will be able to buy pre war spares from the club, or alternatively use you initiative and have some spares made locally in Holland.
You won't go far wrong if you copy the exhaust camshaft that you have in terms of a blank for the missing inlet camshaft, as it will have the same number of teeth. The cam profile should be the same for both inlet and exhaust.
As for the material, you would again need to check with LDMCC or I would suggest that you use a good quality carbon / alloy steel that can be heat treated post machining.
With regards to the pinion, you have most of what you need, as the crankshaft appears to be there, and this gear will be exactly half the diameter of the two camshaft gears, as it runs at twice the speed. The thickness of the gear should identical to the camshafts as should the gear profile. The crankshaft will confirm the dimensions of the enagagement, eg parallel or tapered hole and the dimensions of the woodruff key slot that you need to cut in it. Again this should be made out of a quality high carbon alloy steel.
As this is not a performance engine then you can simply adjust and set the valve timing by moving the gears one to another. Again the LDMCC should be able to help with the valve timing sequence from the library of drawings that they hold.
Lastly the size of the magneto drive pinion will depend on what magneto you have. Does it have one or two pick ups ? This will determine if it runs at engine speed or at the camshaft speed. If you have the magneto then you can work this out. Again the gear will effectively be a copy of either the crankshaft pinion or the camshaft pinion with the same number of teeth and profile. From the magneto that you have you will know what the engagement is. Most have locking tapered shafts. Material would be the same as the other gears.
The allignment of the gears will determine the need for shims and packing or the thickness of any boss at the back in particular on the magneto....
You will find it so much easier if you join the club and source the spares from them.
I hope this helps,
Mike
