I know what you mean, on my 35" scale 4-string Millennium Rotosound Long Scale could be top-loaded but were too short to go thru-body. DR Long Scale are longer in general and ork either way in my 4-string; I can't say about the B-string. DR Extra Long would definitely be long enough; my guess is that so would their Long Scale.
The D'adarrio Extra Long Scale XLS strings are perfect for the Millennium. That's what I put on the Millennium I had for a short time.


