There's a video somewhere on here where Ben tries different values for a 3 string CBG and comes out with a .01uf value, I have no idea whether it would be the same value for your bass........yet! I have the washtub, the pole and the weed whacker string, but she ain't been put together yet.
I did buy an assortment of disc capacitors really cheap from China via eBay, so can mess around with values and find what suits me best.
If you could post some pictures and sound samples of yours, that might give me the jog I need ti finish mine.
Hope this helps