So, we cleaned the tank. Then we made a new tailpipe / muffler. We're going for a straight pipe inside of which we've placed a washer (1 1/4" I believe) perpendicular to the tailpipe walls. It is riveted onto an l-shaped thingy that can be angled so as to increase flow / decrease resistance as one sees fit. We did try the washer trick out on the previous tailpipe (which was gutted) and it made a rather big difference versus running the pipe open. So even though we haven't tried the new tailpipe out, we're confident it'll work. We'll also try wrapping it, see how that looks.
But that was not it. The new seat is as good as finished, only missing attaching a couple of straps that will work to stretch the leather around the seat. The new seat leaves some space between itself and the frame. So we made a little bag that'll attach to the underside of the seat and that fills the newly created space.
The seat nucleus was made of a piece of scrap wood that we had lying around, with some scrap metal from the junk yard wrapped around it. Tools used? Hammer. Canvas and leather for the saddle and canvas for the bag.
Progress pictures for the seat and the finished saddle bag. You can just about spot the tip of the tailpipe too.
Not for Pussies!