I've been playing 4-string bass for an eternity using 45/65/80/100 gauge strings. I've noticed that some string makers don't offer these gauges as part of their 5-string sets, but they do for their 4-string sets. So, I have two questions: 1) What nickel roundwound 5-string sets come standard in 45/65/80/100/xxx without having to make a custom set? 2) What gauge low B would you recommend? Thanks for your help.