Magnum/727 in a early A body.

Well..... maybe. If by early A, you mean 66 and earlier, then "almost" would be my answer. We put a 727 behind the 360/408 in Jake's 65. We had to flatten the seam where the firewall meets the front of the tunnel. Also had to hammer clearance the side of the tunnel just a little to clear the shifter linkage movement. Wasn't that bad. The fun part was, and maybe because of manufacturing tolerances?, we ended up splitting the top of the tunnel from the factory console mount the the firewall seam and then jacked the trans into place. It pushed the split open and we basically did a mini-tub job on the center of the tunnel to clear the back of the bell. Others have not had to do that. Good luck.