I have two sets of these.
Both bought used from different people on The Gear Page at different times.
Both probably come from somewhere in the 1990's.
Both are Genuine Bill Lawrence (not BL USA) with the correct labels.
One set reads about 1k on average higher than the other.
These are all Stacked Humbuckers wired in Series.
ALL of my pickups, all six, read 'double' what you would typically see, because they're Stacked Humbuckers.
My lowest reading is 12k, which results in a 6k sounding pickup, with white/black wires.
My hottest reading is right around 20K, which yields a 10K sounding pickup, with red/black wires.
All the others are somewhere between them, just do the math and 'halve' the output to interpret for the intended position.
A 14K sounds like a 7K, and on and on.
They're all two-wire pickups, and all color-coded for position.
White/black is neck and weakest readings, green/black is middle, red/black is bridge with strongest readings.
If you're getting anything like a regular SC reading (in a 6k, 7, 8k range), I don't think you have Bill Lawrence 280's or 290's.
A BL 280 set should measure out something like this:
12K (white/black, neck, sounds 6K)
14K (green/black, middle, sounds 7K)
18K (red/black, bridge, sounds 9K)