I couldn't get my 727 to fit without cutting the top of my tunnel out and welding in a sheet metal cap shaped on an english wheel. What a pain! I also "massaged" the pinch weld. The clearance problem was in the front part of the tunnel. I couldn't get it high enough to get the trans cross-member in place.
The trans pan is wider too. With TTi headers, there is hardly any room to do anything under there. It is a lot tighter with the frame rails 2 inches less on the early A's.