Lots of surface rust in tunnel

[BK911]

'76 912E.
Master cylinder leak poured brake fluid all over pedal cluster area and through out the tunnel.
By the looks of it, this had been going on for quite a while.
Surface rust is pretty bad in some areas.
Pulled the interior out, all stuff in the tunnel, pedal cluster, MC, and the engine/tranny.
Sprayed the purple stuff all through the tunnel and pedal cluster area.
It cleaned up pretty well, but now I am left with HEAVY surface rust in an area I cannot get a wire wheel.
So now what?

Want to spray something to neutralize / convert the rust.
Vinegar? Phosphoric acid?
Let it sit a day or so, lather rinse and repeat?
Then spray a thinned out POR-15 inside the tunnel?

Any ideas how to attack this?

[Dmitry at Pelican Parts]

Hello - I'm attaching a link to an earlier thread where this is discussed. Hope this helps you a bit.

Center Tunnel Rust Repair