After truing up the keel using the set squares, drive a screw through the brackets to secure and run a filet of adhesive down either side.
If you are likely to pull things apart to pursue mods, use bathroom silicone instead.
Now's a good time for a coffee and without sounding too much like Alan Partridge I have chosen a Krispy Kreme pistachio-flavoured ring-doughnut, and a Dolce Gusto.