I heard 20 hours , but it took me a little longer.
The best advice I got was to go with 10 to 14 inch strips when filling the gap.
Of course I didn't take it at first.
I split the wheel well about 1/2" inside the seam and cut right along the inside of the bottom edge.
then made a cardboard template of the front and rear radius and cut right along the frame rail to where I wanted the radii to come in.
This made for very little patching.....like 1 piece that was a small triangle.
You need to weld along the top edge of the frame rail to restore structural integrity to the rail , then clamp the inner wheel well to the frame and tack it in.
I had 2 7/8ths gap over most of it and and 3 1/8th at the bottom of the rear.
I welded from underneath , so I did the equivelant of 10,000 ab crunches while doing it......and didn't lose a gram !

I used 20 gauge mild steel and with my toaster set on low , could actually run beads ( Lincoln 170 )
Once I was satisfied that the inner well was where I wanted it , I welded it in full length , then did the filling of the gap.
I made wooden wedges to keep the distance roughly where I wanted it as I went and welded in approx. 10 " strips till covered.
There is relocating the trunk hinge supports and notching the package tray brace.
Then mudding , sanding and squirting , so 20 hours seems optimistic.
But it turned out pretty fair I think.....and i got splatter paint to hide what isn't perfect.