Demontweeks normally stock them or ebay.
To find SBS pad fittments, go for the number i.e Fazer front 634, rear 570 on their website, then scroll down and it will give you a list of all the bikes using the same pads. SBS OE fitment is front HS and rear HF. SBS pads are HF non sinter FF, HS sinter, SP = HH, listed as 'street'
Some stockist list pads say for an R1, FZS100, XJR1200/1300 etc but not, FZS600 but they're the same pads, but my not be the same rating i.e. HH for front not GG.
See here
https://www.sbs.dk/products-1/brake-pads/634hsPad ratings or letter codes are FF, GG, HH or HG, GH etc, each letter is a friction coefficient, 1st letter is 'cold' 2nd 'hot'. Fazer std is FF rear non sinter and GG front sinter, most production/street bikes are the same although a lot of pure sports bikes use HH sinter fronts, ceramic is non sinter.
Avoid RST listed as 'racing' these are really entry level track pads, they're not so good on cold/wet or in the wet until heated,
DON'T ever fit their DC, DS-1 or 2, for street use, these are pure racing pads, they need to be hot before they work. i.e. you'll be hitting the first car in front of you as he stops, or you need to be braking twice the distance, I kid you not