Alright guys, I feel like I have fallen off the edge of the world when it comes to progress on the bike; somehow I am letting life get in the way of the build. Hopefully I will get a lot done this coming weekend, but only time will tell.
As for the tank, I began by cuttinG out large knee reliefs in the side. The cutouts go in as far as the inner tunnel would allow, and all the way up to just shy of the petcock fitting. I then cut the back seem of the tank where the top of the tank meets the tunnel. Now that the back portion of the tunnel was free from the upper section of the tank, I bent in the rear tunnel edge walls until they were narrow enough to match the 550 frame. I didn't want to just cut it narrower becuase the formation of the tunnel wouldn't allow it. It is hard to understand what I am saying by just imagining it, so I can try and take some pics to show details.
I then cut two flat panles that fit the new cutouts and welded them in. I decided to do each individual side in two pieces: One large one the was flat and covered the side cutout, and then one more that was placed to make the transition back into the original tank appear sharp. It is possible to form one piece to contour to the coutout, but two pieces are much easier to work with, and helped get the sharper image that I was going for.
Next, I just welded up all the seems that I had cut open to allow shape shifting of the tank. All in all, it was sort of a pain due to me wanting to make it flush at the narrow end with the frame and seat to allow a smooth transistion between them.
Hope this helps. Any more questions just ask, I will try and get some pics of the end tank result that will help my terrible explanation make some sense.