Overwriting rhymes with:
underwriting, rewriting, underwriting, writing, benighting, biting, citing, delighting, exciting, fighting, igniting, inciting, indicting, inviting, kiting, lighting, nonbiting, overexciting, reciting, reigniting, reuniting, rewriting, sighting, siting, slighting, underwriting, unexciting, uninviting, uniting, whiting, writing
Overwriting sounds like:
operating, operation's, operations, operations', overdoing, overeating, overheating, overrating, overriding, overtones