1953 Chevy P/U Suspension

[hale1953]

I have a 1953 Chevy 1/2 ton pickup with a '69 small block chevy. I had a street rod shop install a late 70's Mustang II front end. Everything I read states that you need to box in the frame. The rod shop did not box in my frame. After about 6 months, the nose of the pickup had dropped about 3 inches. My first thought was that the Mustang II front end and springs were setup for a 4 cylinder, so I put new V-8 rated springs. That helped, but the front frame had 2 small cracks that the rod shop had to weld. My question is did this guy cut corners by not boxing in the frame? Will I continue to have problems in the future?

I would appreciate any input. I have invested about $4K into this rig, and I want to make sure the work is done right.