Changing sock pattern

I’m knitting socks but need to change the size - for the men, I usually cast on 64, size 3/3.25 needle and want to size it down to a cast on of 60 stitches. How do I calculate the rest of the pattern - i.e., heel flap, gusset, etc.? Is there a special formula for this? I’ve checked my knitting books, but nothing there

Thanks

Here is a link to something that may be of use. LINK

Thank you so much! That will be such a great help! :hug: