I briefly looked into this at one point.
A video out there uses an Opus 88 with a parallel nib. The Opus 88 is a Jowo #6. It is my understanding that this does not work with every Jowo section. Basically, you would need to remove the Jowo, and friction fit the Pilot in your section. It may or may not leak, depending on the fit. I have read a few times where people have tried this, and it did not work.
There is a second video below that I saved at one point showing the parallel system fitting into a custom pen, but I don't know what threads are being used on the pen. She basically takes the whole unit out of the parallel pen and threads it into the barrel threads. I never pursued this, so I don't know the answer.
I think the better method would be to alter your section to accept the Parallel nib and housing as a friction fit.
Here is one I found on Etsy to give you an idea. Another slight possibility would be to take a look at the flexible nib factory and see if they have a feed for the Parallel that fits into a Jowo housing, but I don't believe they do.