You are not ever going to go back to Opioid naivete. It just doesn't work like that. There is an elastic quality to tolerance/dependence that we all are familiar with because it is obvious. Tolerance goes up and down in a way that is hard to miss. What people have a much harder time understanding, are the permanent effects of Opioid tolerance. I know a lot of people will jump down my throat for using the term "permanent", but I feel it is apt and will lead to better understanding.
If a person has had a long-term, serious Opioid dependency, this is how it works. I use the analogy of the rubber band. You can stretch a rubber band over and over and appears to retract back to its original shape. You stretch it a little too far and it starts to fray. It still seems to snap back to its original shape. Then you stretch it hard again and those frayed points that were seemingly gone are there waiting. They are permanent.
We don't have a lot of data for people who say, went 30 years clean and then went back. Who knows? Perhaps that would be different. However, we have plenty of stories of 1 year, 2 years, 3 years, 5 years, 8 years... These people all fully expect that they are newborn babies after such a long time.
They are not. They get high once. It's not even as good as it once was, but they get "high". The next day, they get even less of those good feelings but are still definitely "high". By the third day, even more diminished returns. However, you are now more or less back to being fully-dependent on Opioids. You are going to have a fully diminished quality of effects by the end of 7-10 days at the very most. By day 7, you're a fully dependent Opioid user as if you'd been getting high every day for the past 10 years.
I'm telling you, don't be stupid. You will be throwing away everything; all of your progress. You aren't even going to get high the way you think you are. You might get one, perhaps two "good" highs before you realize you've fucked up.
This is the permanent quality of Opioid tolerance following high-dose, chronic usage. You can't ever go back. Like I said, we don't know much about the 30 year/40 year people, but then again, those people were smart enough not to relapse, so they're probably even smarter/have lives of substance that they love and enjoy that they wouldn't throw away for a few shots.