Hi! I'd be interested in joining if you're still looking for a composer? I've written a couple of jazz/big band type pieces before: I haven't written any full-length tracks in that style recently, but it's absolutely something I can do. The idea of mixing that style with more gothic music sounds really fun!
Two pieces I've written that have a bit of a jazz feel to them: unlimited shrimp (the harmonies more than the arrangement) and Headless Chicken (an oldoldold track, so it's not super polished). You can hear some of my newer work on Soundcloud and Bandcamp.
Let me know if you're interested! I can't really start work on writing any music until after the weekend, but I can chat ideas through. You can reach me here or on Discord (I'm @sshhaappeess).