While I've never tried this, depending on your budget, you may have an option.
If you buy a Jr. Gent II kit, and a Euro Letter Opener Kit, you should be able do the following;
Cut the Jr Gent II tube in half and glue the ends into a long blank the right length for the opener handle and thus make a really long Jr Gent II cap sans clip. (Or buy extra Jr Gent II tubes and use a pair of cap tubes)
Glue the Euro tube into a piece of scrap wood with a bit of the same wood used in the Jr Gent II cap. The scrap wood is only a tennon to fit into the Jr Gent II cap thread coupler while the other wood is turned to make a nice transition of diameters of the Euro Hilt to the Jr Gent II cap thread coupler.
Glue the Euro opener into the long Jr Gent II cap.
Sounds kinda pricey, and a lot of work, but if the customer is willing to pay for it...
With a bit of experimentation you may find a better letter opener to glue into the extra long Jr Gent II cap.
