Beautiful pen, Lenny!
As far as components, order 20, 50, 100, etc(however many you sell to make the pricing attractive in ROLLERBALLS). At the same time, order 3, 5, or 10 fountains (again, dependent on what you sell). Every vendor has mix and match, so you get the "few" fountains at the same discount.
MAKE EVERY PEN AS A FOUNTAIN! Some things need to happen with a fountain that don't really mater with RBs.
Make sure that the cap posts "in line" for fountain use. Also, make sure that the grain aligns when turning "up the nib" when capping.
THEN, make it into a roller ball, because "nib" alignment means nothing. You get the spring when making roller balls.
If yo follow the above mentioned instructions, the nib will always "line up" (top and bottom , with postables)/
If you later convert to FP. With Jrs, et al, it is a matter of using a dental pick to remove the back spring and changing the front section (while the customer waits- 15 seconds with me).
After a while, you will know how many FPs you should order per 100 rollerballs.