Hello,
The frames are basically the same. I have a 59 frame with a 55 front clip installed on my build. I had no issues with the radiator mounts, my 55 clip bolted up just fine. I cut off about 3 inches from the front of the frame but I don't remember the exact measure. I could get the measurements for you because I still have the pieces I cut off. The easy way to do would be to mount that front clip perfectly and mark were the bottom grill support meets the grill and cut it off even. Thats what I did.
Radiator mounts?
Here is what mine looks like. There are two different kind but that did not seem to make a different for my sheetmetal.
I'm not on this site anymore but someone told me about your questions knowing that I did the same on my truck so I thought I would stop by and help out. Plus I think Sid is good people.
I will get those measurements to you when I get home tonight.