Yeah, Hellyer was on the party's centre-right then but he did have backing from a wide range of the Liberal spectrum, including parts of the centre-left. Most famously Judy LaMarsh.
One of his themes was CONTROL after 5 years of psychodrama and weak political leadership, or as Newman puts it, he'd deal with the bureaucrats the same way he dealt with the admirals. So he can campaign as himself while touting the popular parts of Pearson's record. No mania but I think a Liberal majority is still possible.
In policy terms you'd see a continuation of Pearson's foreign policy, but domestic issues will be a problem. LaMarsh would remain in politics, and as a close ally she'd probably have enough leeway to enact progressive-pleasing policy initiatives. Otherwise the Dippers surge in '72 and quite possibly hand Stanfield the Sussex keys. Quebec is a tough one, and since Hellyer didn't hold a domestic policy portfolio I don't know what his views on it would be. Most likely the confrontational strategy continues, since that fits Hellyer's personality and ROC public opinion would demand an aggressive pushback against the Unionist push for greater autonomy and closer ties with France.