The definitive answer......... here it goes.
You can use a N6 Jowo in a bock feed. It should work, but the opposite is not possible, well, you'll have problems to adjust the nib correctly, this is a bock on a jowo feed, as the feed that's used by jowo is wider, and Bock nibs are a bit narrower than the Jowo ones.....what else, just buy a steel nib and make the try. think htat the nib casings are different, so your conid has a bock case.
Here a link to a german retailer of Bock. it has a good selection of nibs.
I speak german so for me is no problem, but you can always use google translator, Im giving you the link. You can also write to Francis or Werner, they will be more than happy to help.
You can buy nibs at FPNibs this retailer is based on spain and carries Jowo, prices are good.
I think you can try a 14k N6 probably will be something in between. But always use the bock feed.
In general european retailers are cheaper than american ones, goulet pens and american sites of the sort are selling re-branded jowo nibs very expensive.
PD jowo has no titanium nibs.