When published next month, it is expected to recommend a review of NTS assets to end what Reid called the trust's "culture of secrecy" and an urgent look at its "unsustainable" finances.
Calman, best known as the head of the Calman Commission on devolution, may have to rationalise the NTS's 128 properties.
Trust president the Duke of Buccleuch said: "Sir Kenneth has a wealth of strategic and leadership experience. We are enormously fortunate to secure someone who combines that experience with passion for our heritage and who is thus well qualified to guide the trust through the next steps of its journey following the conclusion of George Reid's strategic review."
The NTS annual results show the charity to be in a "more secure" financial position than it was a year ago. Working reserves are £8.5m, up from £4.1m in the previous year. Visitor numbers were up seven per cent. Wages were down 3.2 per cent thanks to cutting 45 jobs.
Reid's review is expected to call for further job losses, cost cutting and potential mergers with other heritage bodies in Scotland. He is expected to advise cutting NTS's 90-strong council and replacing it with 12 trustees elected by the trust's 310,000 members.
Calman will succeed Dick Balharry, who took over from Shonaig Macpherson in January after she left amid reports she was unhappy at cutbacks proposed to meet a £13m black hole in NTS finances.