I didn't think the headbolts were stretch bolts?
Reuse them!
I always replace piston rings though. I've never considered reusing the old ones because I'm a clumsy git and usually end up breaking them when taking them off. So I budget for them when I know I'm gonna be taking things apart.
I bought a honing tool ages ago off ebay. Works great. Whether you use sandpaper or a honing tool, don't be shy with the oil can.