Enough with the research...

Take a lot of measurements before pulling it all apart. Remember that K frame has shouldered bolts and fits "exactly" if the rails are off even 1/16" the bolts wont fit. I would recommend making bracing or a jig that fits the pieces together off the original front clip before pulling it apart. Stiffer the better. Welded metal tubing would be the best.

Best bet when fitting those rails and front clip is to temp bolt that K frame to the rails, then temp weld a brace out of 2" square tube steel across the framerails behind the K frame then remove the K frame prior to installing the front stub to get some weight back off it. Temp hold it together w self tapping screws to make sure its all aligned correctly including the external sheetmetal before taking a torch to it and welding it up.