I'm using a 056 with a 27" scale. Would like to put a 060 there instead, but sadly Elixir doesn't make one. I mainly tune standard though, but every once in a while I drop the B to A. For a long while I used to use the 068's Elixir does make (and 070's before I switched to Elixir), but I thought they sounded duller and didn't "bite" as well as strings that are a bit lighter.
I tried an Elixir 060 bass string once though... Never again. They sound, well, like a bass I guess.
What I'm trying to say is that upping the gauge might not be the solution, but then again, that's just what I've found, might not be the same for you. The Blackjack's a 26.5" scale BTW as mentioned above.