You'd need him to be Leader instead of Heath, quite simply, which opens up it's own can of worms.
If Thatcher is openly Powell's brand of transcendent, protectionist nationalism, then she's unlikely to actually make headway in Heath's Cabinet and be in the position she was IOTL to challenge him. Economically Powellite might work (as in she is a true believer during the Cabinet years), though Europe would be a sticky wicket, but unless Powell is leader I don't see how she could naturally become a Powellite. And even then, I honestly can't see how she would still become Leader in such a scenario. Powell at the helm would likely do more to discredit Powellism than promote it, and I doubt Neave would offer one of Enoch's acolytes a shot at Leadership if it's the disaster it would have likely been had Powell had led the Conservatives, let alone become Prime Minister.
EDIT: Of course, as Meadow rightfully notes, she did admire him (in the Downing Street Years she outright says this, IIRC), and her economic plans bore a markable resemblance to what Powell, Macleod, and Thorneycroft were playing around with a decade earlier.