Chainsaws

I am original owner of a 1984 Husky 61 saw and still use it often.  My question is regarding gas/oil mix.  I believe I remember the owners manual referencing 24:1, but the manual is long since lost.  This is quite rich by today's standards, I get OK plug life and the dome of the piston is not carboned over.  A couple of individuals have suggested backing down to 40:1, but I hesitate to change based on nearly 30 years of use without ever having the head off.  Suggestions?