Looking on the internet deeply has found these results:

long time have gone is the most popular phrase on the web.

a long time had passed 1325,000 results on the web	long time have gone 11,340,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	The time has long gone for simple compromises, which some, moreover, are saying will be difficult to achieve. The times have long gone when the budget came under consideration in one place for six months or so and then for the rest of the year another committee was responsible for budget control. Son, it's been a long time since we've gone to your mum's grave. But such times have long since gone. Two years is a long time to be gone. That samurai is long gone, times have changed. And maybe that somebody is you, come to see us after a long time gone. Planet is going to be here a long, long, long time after we're gone, and it will heal itself.

a long time had passed

1325,000 results on the web

long time have gone

11,340,000 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

The time has long gone for simple compromises, which some, moreover, are saying will be difficult to achieve.
The times have long gone when the budget came under consideration in one place for six months or so and then for the rest of the year another committee was responsible for budget control.
Son, it's been a long time since we've gone to your mum's grave.
But such times have long since gone.
Two years is a long time to be gone.
That samurai is long gone, times have changed.
And maybe that somebody is you, come to see us after a long time gone.
Planet is going to be here a long, long, long time after we're gone, and it will heal itself.