<pics of top tube gas tank and steps
Some one here also made a beauty! I can't find the thread, but am sure some one will know. What is shown at that link is cut the top tube out and weld it You can also, and I think preferably, drill fill and petcock holes and do it all with chemicals and not mess with the paint job. Is really cool. A man named HBlocal came up with it and shared his method freely. Awesome guy. Here is another link to the same concept.Ridley Vintage Motorbikes : Models
Found out it has been being done for years.
grubbe gear box is for 4 strokes, Gear Box Assembly