Head's second-innings 121 in Gqeberha on Thursday marked his fourth hundred since moving to the top of the order last summer, even if it failed to save the second Test for Australia.
It also ended a run of outs for the South Australian, whose string of six scores below 25 since August had threatened to prompt further debate if he was best suited at No.5 or the top.
Head maintained afterwards he did not need to make changes for his century at St George's Park, with the only difference being that he got through the first hour.
His success at No.5 before going to the top means the questions will always be there around his best position, but the 32-year-old insists his mind is only on opening.
"They want me open and I'm chips-in on that. I'm not going to falter or waver off that," Head said.
"As soon as my mind drifts elsewhere, that's not putting the team forward as first and I potentially might not be able to do as good a job as I could.
"I feel like I've started really well in most innings and I feel like I'm close to doing a job each time of getting to that 10- to 12-over period and knocking the shine off."
Head also insisted there had been no internal doubts about the decision to open, even through the flat spot against Bangladesh and South Africa.
"I'd love to go on and get more runs, and I've been disappointed about that in the last couple of weeks," he said.
"I've been desperate for runs. You always want to start the summer and get into it and contribute all the time.
"But I haven't faltered on that and I'm not wavering."
Who opens with Head at Newlands in the coming week remains one of Australia's biggest decisions.
Matt Renshaw looms as most likely if Nic Maddinson is dropped, but the Queenslander's heroics in Durban had initially prompted Australia to keep him in the middle.
Head's old No.5 role has become the best to bat in for Australia over the past five years, with the fit-again Cameron Green scoring a century there against Bangladesh in Darwin in August.
That situation has been replicated across world cricket, with Head pointing out positive counter-attacking batters had thrived there given they could walk out at 3-30 or 3-300.
But he also insisted the move to open should not bring about a significant change for anyone, after scoring his runs at the top with the same approach as a No.5.
"Batting's batting. I don't see any difference in one and five. For me, it's the same process. It's a red ball still coming down," he said.
