I did a complete long term withdrawal off h when I'd been using up to 1g a day for 2.5yrs. It was over within about 5 days, but the first 3 were really rough. And I had benzos & the strongest anti nausea meds, anti diarrheals, plus a few other things I find helpful (pseudoephedrine). I actually found the cimetidine (which I was using to potentiate) WD was worse, and I no longer use it for that reason. I take shorter breaks more often now to keep my tolerance down, especially since I'm using for pain & I'm terrified of having nothing that helps. I always taper but usually pretty quick tapers over 1-2wks.
I haven't tried using nalaxone but I'd like to try ketamine for tolerance.