Your don’t need to weld on your flanges. They all use snap rings to retain the flange on the headpipe. As long as you have the short, larger step right at the end that stops the snap rings from sliding right off, your good. If I remember contractor, M8, twin cam and evo use the same size flange anyways, so it might be a moot point.
In any case, you might be further ahead to find a used exhaust system on Craigslist or eBay and start cutting where you need. Then at least you are starting with some bends and can get closer than starting with straight tubing. I’ve made a number of exhaust pipes for bikes over the years like that.
2018 FLTRXS Wicked Red
Harley Master Tech at Hampton Roads Harley in Yorktown, VA
Disabled Combat Vet - JTAC 96-06