Hi, we're looking for the best way to accomplish something that might be a bit uncommon.

We have a concrete factory floor 8" thick. There's a raised concrete section about 600 sq. ft. that's 9" higher than the main floor (so in that area it's 17" thick), that we want to reduce to the level of the main floor (remove 9" of the 17")

We believe it was all cast at once so no cold joint.

I'm thinking we use a hydraulic breaker on our skid steer, then a walk behind scarifier to knock down any small high spots, and then skim coat any low spots.
Seems like it's going to be a lot of work.

Would be cool to build a diamond wire saw flush to the floor and cut it off, but there isn't much space around the raised section...
Feels like what we really need is a scaled up scarifier- something that'll cut off 1" or more at a time at a decent pace. Is there such a thing?

Any clever ideas how to accomplish this more easily?