From 367 for three, New Zealand are ideally placed to press on to what would be a first test win under McCullum's leadership - and first since Taylor's final match in charge last November.
They will start today with their stand on 182, both have centuries against their name and their double embrace as each hundred was reached was no doubt heartfelt.
In their own ways they've been through a mental and, in McCullum's case, physical grind in the last year.
McCullum, whose family were looking on, was emotional in the dressing room, a mix of relief having put a run of low scores behind him - which he felt was hindering his ability to lead from the front - and discomfort from his troublesome back.
His batting is never dull, and he makes his runs at a merry clip.
McCullum reached his century in 101 balls, including three sixes, just beating Taylor to the mark, and once he found his range produced a flamboyant array of shots. His feet were moving him into position swiftly and he flogged some ordinary West Indian bowling.
Only once, when he attempted a reverse sweep, did he veer off message, but for good measure - and as if to demonstrate his growing self assurance - did repeat it shortly after for a boundary.
Taylor had a scare on two, looping an edge off a lifting delivery from the indefatigable Tino Best just over slips. Again, once he got going, he too enjoyed himself and made sure he took full advantage.
Taylor's made no secret that he took the loss of the captaincy hard, as anyone with a sensitive bone in the body would. But yesterday felt good. "Yeah, a good feeling is a nice way to sum it up," Taylor said.
"It has been a while since the last test hundred and it's nice to be there at the end of the day and to battle the demons that I probably had in my first 20 or 30 runs."
Taylor once more had to bury the idea that somehow he and McCullum are rivals.
"No, we're teammates. We want to do well for the team and the country.
"There's always going to be that comparison until he retires, or I retire, but we can't control that. We just have to do our best every time."
As for McCullum, "he's knackered".
"I think when you're captain there's a lot of emotions that go through you before the game. I think he will sleep well tonight."
Taylor admitted he has a target of test hundreds in mind, but will keep it to himself. He had a chat with his mentor Martin Crowe the night before the test.
"He's been very good. He was just telling me to relax, get out there and enjoy the battle."
It was a day to savour for New Zealand. Peter Fulton and Hamish Rutherford continued what's becoming an impressive opening partnership, this time putting on 95.
Aaron Redmond's comeback ended unluckily, a leading edge lobbing to gully.
The batsmen have had far tougher days. The West Indies bowlers butchered first use of the new ball in green, helpful conditions and once Taylor and McCullum settled in they ripped the initiative away from the tourists.
The platform has been laid by the batsmen; now it's about pressing on.
By the numbers
*The unbroken fourth-wicket stand between Ross Taylor and Brendon McCullum of 182 is seven runs short of the New Zealand fourth-wicket record against the West Indies, set by Mathew Sinclair and Nathan Astle at Wellington in 1999.
*It was Taylor's ninth test ton, and first since his last test as captain, against Sri Lanka in Colombo last November.
*It is McCullum's seventh test century, and first since November 2010.
