The 300's pump is like the one on my 100 Farmall; except mine uses a seal instead of packing. With all the pumps I've packed, small to large on many applications, they all used rings you had to cut. The packing all comes spooled unless pre-cut, which is rare. Coiling won't do as good a job as you won't get an even pressure across the circumference of the gland, but there are some who do it that way I suppose. Teflon would be my choice followed by graphite impregnated. From looking in the parts manual across a few models, lantern rings aren't seen in some tractor water pumps.