I have done searches and found a few responses on an A8 mag in a JB.
I have a Parker Fly Mojo that came with Jazz/ JB. It is not easy to swap pickups in the Mojo (you have to cut the mounting screw brackets off, so you can't resell the pickup), so I'm doing some mag switching first. The Jazz was just too bright for me in this guitar, & the JB is very miiddy & honky (no offense whatever to JB fans, many make them sound great, they are just not my pickup).
I put a uoA5 in both the Jazz & JB for starters. The Jazz is now my neck pickup from heaven- smoother but still chimey with an improved low end. Sweet is an overused term that describes it very well!
The JB with the uo A5 is smoother but just lacks character. I think an A2 would be too low ouptput for the bridge in this guitar, + lacking in tight lows. So I'm interested in the A8 in the JB. Some love it, some say too hot (I would be very wiling to keep in low). I do play some clean & blues, not all hard rock. I also do coil split the bridge pickup. What do you think about A8 in a JB? (guitar is very lightweight but is all mahogany with mahogany neck).