Best thing to do is choose a piece that you like, with the number of required parts, and arrange it for your gropu yourself. Unless a piece is written for THAT specific instrumentation, you won’t find it, especially if it is not a common arrangement, like a string quartet (violin I, violin II, viola, cello), French saxophone quartet (soprano, alto, tenor, baritone), horn quartet, clarinet chior, etc….the list goes on.

A good place to start might be:

Try this website, it’s a bunch of chamber music databases. I haven’t tried it myself, but you may have some luck.

Other than that, try to access the library search engines online of performing arts schools. Some may allow you to search their databases. The Hartt School of Music’s Allen Library has a pretty good search engine, you start there.

Also give the Library of Congress a try:

GOOD LUCK!

If you can find such a website, there is no guarantee that you can get the sheet music or a recording. Unfortunately, there is enormous amounts of classical music that is not very good. We all now that there is enormous amounts of songs on the radio right now that are not very good and will not make the top 40 list. Unfortunately, earlier generations of classical nusicians wrote just as many peices of music that have not stood the test of time. (I know because I had to listen to some when I took music history to get my college degree in music education.

I applaud your notion of accessing the internet for such things, but the search engine does not necessarily guarantee you a perfect fit. You will have to resign yourself to the task of customizing (transcribing) any arrangment that is already out there, especially if your instrument configuration is non-traditional.