Finally got around to do some work on the FB again, after a long time installing a complete TCP suspension setup on a friends '70 Mustang.
I removed the rest of the main floor, boxed the frame rails where the transition pan will sit, did some rust repair on the LH rear window corner support, removed the LH wheelhouse and quarter panel. The inner wheelhouse will be widened by about 1-3/4" to accommodate wider wheels.
I initially wanted to keep the original quarter panels, although they have quite a lot of small dents in them, but after test-fitting the new quarter panel skin from AP, I found it to be a near perfect fit, so I have decided to replace them.