似た用例を有名文学作品から探してしてみたわ

He was a long time going to sleep. After a while he turned and looked at the man.
(Cormac McCarthy The Road)

He was a long time knocking before there was any sound at all within the house
where Sheila and Mona lived.
(John McGahern Amongst Women)

, when my uncle hadn't gone to Coik and my father was a long time in Macklin's.
(William Trevor The Raising of Elvira Tremlett)

He was a long time resolving definitely to ask her to marry him.
(D. H. Lawrence The Rainbow)

He was a long time before he got to the top. But he got there.
(James Joyce A Portrait of the Artist as a Young Man)

She knelt down beside him. "You in trouble?" He was a long time answering. "Yeah," he said.
(John Steinbeck Grapes of Wrath)