Modifying a pipe is a pain in the a$$. I ended up spending a couple months learning the ins and outs of expansion chambers so I could modify one to fit in my K5 LT250 combo also known as "Goatzilla" If I had to do it again I would build a pipe from scratch or make the frame fit the pipe like you are.
Where are you located? I'd run scrambles with ya either on the KDX4 or Goatzilla.