Crown lawyer Erin FitzHerbert (EDS: CRRCT) pushed for a sentence of preventive detention because of the clear pattern of offending that had spanned decades.
There had been a "gross breach of trust" of vulnerable victims and there was a sophisticated level of grooming involved, she said.
Linton's lawyer Mark Callaghan said his client viewed a period of preventive detention as a "life sentence" because of his age and he would have no motivation to attend rehabilitation programmes.
His client wanted to be given a chance to attend a course and receive treatment, he said.
Justice David Collins said it was important Linton be able to have access to an intensive rehabilitation programme, which would give him an insight into his offending.
But he said Linton had come "perilously close" to receiving the open-ended sentence because of the pattern and history of his offending.
"You are clearly a very predatory offender."
Linton had befriended his victims' parents and groomed the boys for his offending, Justice Collins said.
He had babysat the boys and offered them all employment.
"The impact of your offending against your victims has been immense."
In 1996 Linton was jailed for 18 months on charges "almost identical" to the latest ones, he said.
In 1967, he was sentenced to three years' probation for indecent assault charges against a boy aged under 16.
