Big Splits work great in Lakland 5501's.......they are P2 Bart shaped.......4 1/4 inch by 1 1/4. Bart makes a MK5CBC 4 1/4 by 1 1/3 which fits the 5501 even tighter.
If you use Nordy PU's for a Lakland 5 Jazz type, make sure they are Fender sized, Not Sadowsky, Carvin, etc. who use 4 string bridge dimensions for their 5 string PU's.
Most folks on the forum know these things, but if you have never modded, you might not know.