I think it could be good news for you Von......I really don't know if your 75 bike is the same as our early 80's bike, but ours has an exhaust "stub" bolted to the barrell, and the pipe is then held onto that by springs. The distance from the exhaust port to the bottom of the engine is quite small, so it may be difficult to find a header from another machine to do the job as the bend will be tightish, and also the pipe diameter is pretty big....I didnt measure it but it looks to be 50mm or so. If your bike has the same stub arrangement, then all that's needed is some stainless tube with an ID the same as the OD of the stub. Weld on a couple of loops for the springs and you've made a start.
Check out ebay, as certainly over here, we have many angles on sale regularly, and it can't be too hard to join a couple up to create a header.