Not sure how to pick a pickup for my violin.

ada

Yous is a common question that is not that easy to answer. Fiddle players contend with it all the time if they play in bands. You can spend a lot of money and still not have a good outcome. My advice is to go as simple as possible. Get a Shure 58 microphone or one like it, or better yet borrow one, and see if you can go directly into your uncle's amp. His amp might only accommodate a single pickup and if so you will have to get an amp, hopefully borrowed. Then try playing thru the microphone and see what happens. If you get a good result that will be a cheap way to go. Also, you might have to lower the treble and raise the bass to get a full sound. Violins are hard to amplify and get a good sound.