I took the foot peg off and looked around for something to use as a bending jig. I found a 19mm socket that looked about right which I bolted to my work surface. After heating the piece with a torch I bent it around the socket by hand. You can see my first attempt was less than great. By using a set of welding clamps I was able to get a tighter bend much quicker. I used the foot peg to check the fit as I went.
I then cut the pieces about 1" longer than the foot peg and laid out a series of hash marks for the grooves. I used an angle grinder to cut the grooves but as you can see it's not a precise piece of equipment. Maybe a bench grinder would be better or even a hand file.
I ground down the height of the piece where it contacted the foot peg to make it easier to weld. I kept the top of the new piece flush with the top of the existing foot peg so it would bear most of my weight. After welding and some paint they are ready to install. (The paint helps hide my amateur welding skills.)