It is certainly no JS100/1000; both of them had the coil split
But your description sounds like a white Radius to me, which evolved into the JS line in '91. Those are awesome. Pics please!
Which pickup layout do you have? HH, HSH or HSS?? Is there just the IBZ-Print on your pickups, or something like "IBZ V2" or "IBZ/USA"? This will help us designate whether it's a R540 or R440.
PS. Yeah, splitting the pickups shouldn't be a problem. The only thing you'll need is a DPDT push/pull switch and some inspiration from the JS100 wiring.