McGregor is expected to miss the remainder of the season after suffering broken ribs and a bruised kidney in a collision with Mohamed Diame during last month's defeat at West Ham, meaning that Harper is Steve Bruce's next port of call.
The 39-year-old was signed on a free transfer from Newcastle during the summer to provide back-up for McGregor, but he has gone on to make 14 appearances in all competitions for the Tigers this campaign.
Harper amassed a wealth of Premier League experience during his 20-year spell at St James' Park and Davies believes that Hull will be in safe hands with him between the sticks over the coming weeks, including the FA Cup semi-final date with Sheffield United at Wembley.
"If you don't have to say too much about a goalkeeper then it's always a good thing and that's often the way with Harps," he told the Hull Daily Mail.
"He's pretty straightforward with how he wants to do things and sometimes that's what you need.
"He's not going to come back into the side trying all sorts of different things. He doesn't try things that don't come naturally to him. He keeps it simple and that's all we need.
"As a number two his experience is huge. Coming into the team doesn't faze him.
"He's not been sitting on the sidelines sulking when he's not been playing. He's been waiting for his chance and wants to take it. The way he talks to the lads is very good, both on and off the pitch.
"It's just his experience, he's got good quality as well. He knows exactly what he's doing."
Davies also spoke of his faith in reserve keeper Eldin Jakupovic who has recently returned from a productive loan spell at Leyton Orient to offer back-up to Harper.
"There's Eldin back in the squad and he's another top-class keeper," he said.
"If Harps was to go down, we've got another quality goalkeeper waiting for his chance.
"Allan will be missed, don't get me wrong, because he's a very good keeper who's had a good season, but that's football.
"You roll up your sleeves. Luckily we've got a strong squad and we're able to deal with it."