It sounds like you aren’t afraid to spend money to make the car right, which is good. I would strongly recommend a transmission flush and fluid replacement if it has not already been done. A lot of forum members by Bosch camshaft position and crankshaft position sensor‘s to keep in the vehicle in case of a breakdown. You can search www.car-part.com to find original parts from salvage yards across the United States and Canada. Many of them will ship parts and prices can be better than eBay. Speaker options can be limited other than adding a subwoofer and separate amplifier but it can be done and there are posts hear from members Who have done speaker and stereo upgrades. LED bulbs are pretty cheap with multiple options from Amazon and you can search this forum to find which bulbs to use in which locations. For now, I just replaced the map lights, license plate lights and running lights.