Don't take this the wrong way, but welding in a new frame portion is not something the average guy does in the shed, let alone going hog wild without knowing exactly what the procedure is, your cutting the frame off a truck, but don't know about the cab bolts? IMO frame repairs on newer truck should be done at a professional shop and they have the ability to get the frame to pre-collision specifications, you could be doing all the work for nothing. I have built many many things over the years, but if i had any frame issues of that severity, i take it in. did you take it in and have it out on the lasers? is the frame fixable? how much did they want to repair it?
I'm out for good.