Mike Allsop has unfinished business with Mt Everest.

The 43-year-old knows about running at extreme altitude. He ran the world's highest marathon next to Everest and over the Chola pass in his buildup to completing seven marathons in seven days on seven continents in February.

"It was the same course Lisa [Tamati] and I are doing but unfortunately my GPS watch froze so I couldn't send the data to Guinness," said the airline pilot. "My spot tracker was okay but not good enough for the record books. I also ended up with a stress fracture in my lower spine after the run."

He went on to be the first Kiwi to complete the 777 but "knocking the bastard off" and earning his place in history stays with him. "I guess I have some unfinished business."

Allsop, who climbed Everest in 2007, described the summit as "unreal and very scary".

"I wanted to get down as soon as possible as I was so far past my comfort zone and so much could go wrong on the way down resulting in me dying."

Understandably, when he pitched it to Tamati she said: "You are as nuts as I am".

Allsop said the idea to take on the alpine run was all about pushing himself to the limit.

"I wanted to find out just how strong I was because you don't know how truly strong you are until strong is your only option.

"It's a huge challenge in so many ways. The altitude, the remoteness, it's extremely tough running at that altitude. You are literally pushing the limit of human endurance both physically and mentally. I believe we are limited by the limitations we set upon ourselves."

It has only been four months since he ran the seven marathons. He has been resting for the last couple of months and letting his body recover.

"I'm now slowly cranking up the training and looking forward to getting into it."

Allsop will guide a team of 14 people to Everest base camp, where they will stay the night on the famous Kumbu Glacier and climb the same peak where he and Tamati will start their run.

He has reached the summit once at Everest and been to base camp guiding treks three times. Each time the mountain presents a new challenge. "I'm actually both nervous and excited, and ... a little scared. But hey, adventure begins at the end of your comfort zone. I would be one proud little Kiwi if we make history."