I have similar size ficus benjamina, and needed both root prune and chop, so first i had a look at the roots, they were potato size, took me 2 repots to get ride of them.
After i could see growth again, i let it grow and mid summer i chopped, half what initial desire was, also hard prune branches but leaving some foliage on them. it survived everything so far and its growing well, this year i will chop it further down to desire size - btw you will get a lot of new growth on lower parts after first chop, so design might slightly change

that happens to me and i do not regret it.
on top of that, they root very easily even thick branches, you can have few more trees

so now im a spring no. 3 of entire operation
Good Luck.
I would repot and chop it first at the red line -
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