Normal priorities could be subdivisions of larger priority levels.
real-time
system
user
batch
idle-eater
That could be about 195 levels total if we keep the same numbers.
Alternately, the standard priority levels could be spread accross
all 5 larger levels. That means 7 normal priority levels each.
The user level would hold standard priorities from -3 to 3,
the batch level is from 4 to 10, and idle-eater is 11 to 19.