Gary;
It's been a while since I've had my old SBWII records on the turntable, but I am not so sure that 'Help Me' is minor. I suspect it leans heavily on the pentatonic blues scale giving a strong impression of a minor, but I suspect there are dominant sevenths (ie with major thirds) being played down at the bottom end.
There is a lot of blues that sounds minor, but is not; the flat 3rd in the blues scale, when stacked on top of a dominant 7th with it's major third, creates what you'd have to call a 'sharp ninth' harmony.
Having said that, it is possible to play 'Help me' in third position over dominant 7th chords (I know someone is going to jump on me here for my terminology)
It works for some tunes and not for others though; you just have to be careful, 'cause in the blues. there are no strict rules beyond taste.
RD