I'm pretty sure it's a straight right-angle.
AFAIK they do not recommend this but maybe they made this new fangled development since?
I recently slapped a set of Labellas on my 70's RI P and it came to life. I'd love to give my 51 the same treatment if poss. (currently wearing DA chromes)
You'd think as they marketed as the original flat wound string.... they'd fit on an original string thru Fender? -shrugs-