"I think Gary is capable of reaching that sort of target.
"We're going to need two strikers and I think they are going to have to weigh in with 50 goals."
Details of the fee have not been disclosed by either club. Hooper cost Celtic £2.4million when he joined from Scunthorpe in 2010, and was the subject of interest from Norwich in January.
Former Celtic captain Stiliyan Petrov is confident the Scottish champions would be able to cope without the star striker.
Petrov is backing manager Neil Lennon to attract a suitable replacement should the deal go through.
Petrov said: "As long as Celtic get enough money, and they are happy with that and the player is happy, I don't think it will be a problem.
"Celtic always attract good players and, if he goes, there will be somebody else who will come in."
