Finally fitted the ST170 300mm front brakes!
Thanks to JDM for sorting it.
Bought it all brand new, calipers discs and pads on eBay for a good price 😀
Can’t try stopping hard yet, because the pads and discs are new, so still don’t know how good they really are.
But, man, don’t they look massive!
(Comparing to the 260mm it had on previously, or the 240mm it had originally!)
And eBay is a great place, isn’t it 😀
Update: brakes bedded in and I tried it hard. Stopping distance is good, but pedal feels a little bit soft. Impressed overall.