Yaser Sb. First of all, congratulation on getting the beast to run under its own power.
Regarding the exhaust, many years ago when I was a fabrication shop supervisor, we used to make a templates for complicated fabrication jobs at the plant in addition to working with the usual manufacturing drawings. The template allowed the fabricator to visualise the job. The template is nothing fancy. Just a wire bent in the same shape as the required pipe. In your case you need to get a stiff wire and run it from the engine to foot pegs or wherever, bending it in the way you want the exhaust to be. Then you ask the silencer walla to use the template and bend the pipe in his pipe bending machine to create the shape as per the template. The final result will be 90% correct. Some final tweaking will be required. Something like this:
