We have never had a problem shopping for the long tights with chamois in...
We shop usually on line, or by catalogue...
In the shorts with chamois page/sections... there are almost always choices of...
- normal length shorts,
- below knee/calf length long-shorts and;
- the full down-to-the-ankle length pants
... all with chamois
If you are going into a bike shop, ask - they may not stock out of season stuff, and may have to order in for you.