I've had major problems finding screws that are long, but have very small heads that fit in the ears of the pickup. I eventually ordered what I thought was the correct screws on eBay, but when they arrived, they turned out to be shorter and smaller than described. I'd waited three weeks for them and I was anxious to get the project over with, so I installed a 1/2" plate and some very thin foam into the cavity and screwed the pickups to it. It's not nearly enough......From what I can see, I need another 1/4" of height, so I'm busy cutting an additional plate right now.
Some time over the next year, when money permits, I think I'll rebody the bass as a proper Telecaster bass and dump the guitar body. When that happens, I'll either order the correct pickup mounting screws, or more likely get Mike Reilander to wind me a proper vinatge Telecaster bass pickup. What I'm doing right now is a make-work project to keep busy while I wait for the new Ric pickups for my current Tele guitar build to arrive.