You don't give enough information.
How big? (Huge doesn't fit a willow tree)

Seventy feet?

How close to a building?

Near house and garage, but the tree is top-heavy in the rearward to
the field direction.

Any overhead wiring nearby?

Nothing. It's on the opposite side.

Have you ever cut a tree down before?

I've cut down a dead crab apple tree, and some half-grown black
walnut trees, and some half-grown maples. I've only got an electric
16” but I’ve been through trunks about the same size with it. The
height is my problem.