I hope this helps...
I have a BTB 575 and use d'addario chromes. Long scales are too short although they physically fit, but the silks on the chromes sit in the nut.
Remember, the bridge on the BTBs is different for each string and the ball actually sits inside the body. This will add to the length that you need, almost like a string-through-body design.
I can't comment on the guages because I'm switching from a Long scale Regular guage to a Super-Long Soft 4-string set with a Super-Long individual B (132). This should give me close to a balanced set of tensions.
What I have now is a standard 5-string Long Regular set (45-132 i think). They are OK, but the volume is different accross the strings and the E is a little muddy to my ear. I'm hoping that the 95 E on the Soft set will be a little brighter.
My first set of strings on this bass was the d'addario Nickels. I liked them, but decided to switch to flats.