Here is my take on this matter....must just say, that I am no expert.
I would harden at 1020 deg C to 1040 deg C. Then temper the blade at 200 - 250 deg C. To get the spring down to 45 - 48 HRc, temper at 620 deg C, although I would aim for a slightly harder spring of about 50 - 55 HRc, at 550...