It sounds like you had already made up your mind before you posted your question. I give you many points for having a good heart, but will caution you that you are entering into an area that you may not be all that familiar with.
Your willingness to help your fellow man is exceptional and well meant, but it appears that you do not understand the consequences that your personal intervention into an unknown situation will bring onto you and your family.
If, as you state, you need to call 911 before you can intervene, then you are placing yourself at risk. You can do many things to help an OD victim that do not require you to interject yourself medically into the situation. Open the airway, treat for shock, etc....
Please, leave this to the professionals, they are indemnified for there actions, you are not.
If you do not understand indemnification, then look it up. You may be placing your family and yourself at civil liability when all you were intending to do was to help.
If you wish to help, become and AEMT, join the volunteer ambulance corps. in your area, protect yourself and your family from tragic loss when you are trying to do the right thing.
HTH.