He did play an EB3 for a while. IIRC it was a '67.
Yup, though not in the 60ies. It was a good bit later, EB-3s had already gone out of fashion by then (yet golden nail polish with men was apparently all the rage):
No idea whether it was used on the actual sessions for Goats Head Soup (an album I like for its sheer over-saturated decadence, I'm not an Exile on Main Street fan at all, sorry all you Stones fans) though the bass on Angie sounds like it could have been an EB-3 (the audio sounds like pick playing to me, but Bill fingers in the vid). OTOH, Bill was really good at dialing in that same nondescript and plain sound no matter what brand of bass he played.
(Not a knock, I like his bass playing, but much like John Deacon of Queen he was never obsessed with having an individual instrument
sound.)
I once read that he didn't like the EB-3 at all and ditched it after a US tour. If you are not going for an overdriven/distorted sound nor for the brittle plonk of the minibucker, an EB-3 does not exactly enhance your audibility on stadium and arena stages.
