Hi Stephan,
If I was you I will go for catharpins similar to this:
Either De 7 Provinciën style:
or Prins Willem style presented in H. Ketting book.
This is similar way I did on my model.
Distance between deadeyes is just smaller and with knot in between to lock it in place.
This is another detail of rigging very poorly documented.
However above examples looks to me most interesting.
This is another situation... where you will just have to decide, which one you like most and just do it
In term of lower catharpins... hmmm there is no real evidence on any plans of Prins Willem where are they shown to be fitted.
Ok... they are visible on the photo of the model, which you posted... but I never seen them in Batavia, De 7P, Willem Rex, Two Decker...
...but if you like them.... probably no one will ever question them
another poorly documented part of the rigging... unfortunately. However, I'm not sure now where... but I think I read about them to be "British" invention and used mainly in this fleet and on big warships... but I can't support this by any source... maybe one day I will find out where I saw this.
If you decide to do them... they have to be rigged in specific way... Mondfeld has drawing in shroud section.
Also your shroud trucks are to low on the shrouds as far I can see on the photos. Look's like you have them at 1/3. If you look at the PW plans they should be around half way between futtock stave and upper deadeye. Adding another set of trucks will look odd... so either keep them as you have now or just cut of and rig it bit higher.
Cheers,
Matt