VHT do a high temperature spray can that you can get from most auto stores (Supercheap/Repco/etc). Whatever you do just don't use their clear unless you're going to bake them in an oven as the clear won't harden properly and brake dust stick to it like glue.
If you want a nice finish you'll have to file/polish the casting first before painting otherwise it'll be all rippled.
I did find some 2-pack high temperature caliper paint that I used on my previous car, except the supplier no longer brings it into the country and it's hard to get anyone to ship internationally as is classified as a dangerous goods.