On a 71, K1? I think they are held on by the circlip above the seal. In fact it is recommended that you do not remove the allen in the bottom of the lower leg. Has nothing to do with getting the lower leg off.
Gotta remov the tubes from the triple clamps, then I'd drain them thrugh the top pour iy out, remove the spring, then remove the circlip above the seal. Then hold the top tube in one hand, the lower leg in the other, collapse the two together and vigorously "pop" them apart. Be prepared for an unholy mess of oil and goo. Pop them apart outside if possible and don't wear your Sunday best.
The K0, K1, and maybe early K2 were completely different than the later ones.
OCICBW but I don't think so.