Gas line installation

After sitting for 40 years, I'm getting ready to replace my old cruddy tank to engine gas line with a new stainless line on my Skyliner. I had to cut the old one in 2 places just to get it out and now i'm trying to figure out how to get the new one installed in one piece. The hardest area to deal with is towards the rear where it crosses between the top of the frame and the bottom of the body. There isn't enough room to get the line with the nut through this little opening. I was thinking I might be able to loosen the bolts that attach the body to the frame on the left side and jack the body up a few inches to thread that line through. Has anyone ever done a gas line replacement on a '57? Any tips would be appreciated.