'long time acquaintance' is correct and can be used in written English.
You can use it when referring to a person with whom you have been acquainted for a long period of time. For example, "My long time acquaintance and I go way back - we've been friends for nearly 20 years."
"Jamie is completely honest, but he can play rough," a long-time acquaintance said.
A long-time acquaintance of Bird ribbed the Pacers' coach yesterday after Indiana practice.
The decision by prosecutors came after Los Angeles police presented a potential felony burglary case against the troubled actress and two men who were reportedly at the Hollywood Hills home of a long-time acquaintance after several items went missing.
When the US expanded its sanctions on Thursday to include members of Vladimir Putin's inner circle, one name in particular jumped out: Gennady Timchenko, a long-time acquaintance of Putin who rose from relative obscurity to become one of Russia's richest men.
Like Mr Kovalchuk, he is a long-time acquaintance of Mr Putin, the EU says.
VaxGen Chief Gordon is a long-time acquaintance of Philip Russell, the former chief of Army medical research.
Hadley, a long-time acquaintance of Stefansson's, was entered in the ship's books as carpenter.
Abu Bakar employed the service of a Chinese contractor and long-time acquaintance, Wong Ah Fook, to oversee the development of Johor Bahru.
A long-time acquaintance, with the advantage of a more distant vantage point, adds, "Those two are still competing, even with her mother long dead.
That might occur if, e.g., the aim is to explain why Peter talks to Twin Pavarotti as if they were long-time acquaintances.
Not all of the victims and suspects that knew each other were long-time acquaintances.
