For your 4 string drop B set, you could build a set from singles, and use the
daddario tension chart pdf to choose gauges that have equal tension on each string.
Circle K Strings sell sets for drop tunings that are designed to have equal tension on each string. For example this set:
4 String Set - Drop Tune Standard 136
.136 .092 .068 .049
There is a big choice of gauges on this page:
standard-drop-tuned-4-strings
They are excellent strings, there are reviews in the Circle K Strings thread.