welding on unibody

Thanks for all the input guys. The thing that made me wonder was the car that Dale Snoke did with Steve Magnante. The 64' Dart gasser "Identity Crisis". They welded the spring perches for the front leaf springs right to the stock frame rail under the torque box and added about 3" to the front of the frame to mount the spring shackles. I would add pics but I can't figure out how lol
Check Mopar Max Dart Attack