I just did some quick measurements on a Schmidt #5 vs a Jowo #5 feed housing. I won't give you the numbers because they aren't something that you can take to the bank but I can say this:
1. For every diameter other than the thread diameter, the Schmidt is somewhat larger.
2. The threads start at almost exactly the same distance from the front of the housing.
3. The Schmidt is slightly longer.
You could probably make a section that is swappable between the Rolling Righter and a Jowo but I suspect that the Jowo would be a really sloppy fit.
The Schmidt is a quality nib although there are many who would view it as being in the minor leagues compared to Jowo or Bock. Schmidt nibs are made in Germany (quite possibly by Jowo). Schmidt nibs cost 6 or 7 bucks; a Jowo or Bock will cost you 20 unless you are buying 50 or so at a time. You can tune a Schmidt nib to write as well as a Jowo or a Bock; of if you can't tune it you can afford to throw it away and grab another one.
There are fountain pen snobs out there and I'm probably one of them. All of the pens I make have Jowo nibs that I tune myself. But I started out with Schmidts and learned to tune on them. Better to make your mistakes on something relatively inexpensive.
Anyhow, I've gone on too long. Hope this helps.