This is not a good idea, so don’t even bother to look.

Even if you could find such an entity, you would have to assure yourself that it had no outstanding or contingent liabilities, and no one is likely to give you a financially viable warranty on that question.  Assuming it is a corporation (and not a trust which raises a lot of other issues), you would need to be sure that there are no current members, and that you have the resignations of all of the directors.  You will need to review, and probably revise, the articles of incorporation to state a new charitable purpose, and the bylaws to reflect a new governance structure.  (See Ready Reference Pages:  “Articles of Incorporation Establish Basic Form of Nonprofit Corporations” and“Bylaws Function as ‘Constitution’ of Nonprofit Corporations”) You might need Attorney General approval for a change in control.  It may have lost its charter if it failed to file state reports.

If the organization has been inactive for a while, it may no longer have the public support to avoid private foundation status. (See Ready Reference Page: "Calculating Public Support Percentage") If it is one of the more than 200,000 (c)(3)s that didn’t filed a tax return in the last three years, it may not even be a (c)(3) any more. (See Ready Reference Page:  “IRS Announces One-Time Relief for Nonprofits Failing to File”)  You would have to file a new Form 1023 application for recognition of exemption if its status has lapsed, and are likely to have to notify the IRS of a change in purpose and operation of the organization even if it hasn’t.  At the very least, you will have to get a new IRS letter recognizing your new corporate name.

It is much cleaner and less risky to start your own corporation and form it in the way you want to do the things you want. You can file your 1023 so that your recognition of (c)(3) status is retroactive to the date of incorporation, and donors will be able to claim a deduction for their gifts. Private foundations are not likely to make a grant until you have received your recognition letter, but they would undoubtedly want a lot of financial and historical information about the group you took over and your application might be tainted by its history.

Save yourself time and money. Start from the beginning and do it right for your organization.