I have also heard good things about the ECSD from Dr Greenthumb, but have never grown anything from him. If you look at some of the other American breeders you will probably find some crosses that will have ECSD in them crossed to other Chem crosses where you will more then likely find straight ECSD phenos. Check out Top Dawg seeds , he just got back into the game and should be coming out with a lot of crosses here soon. He supposedly has the best of the best when it comes to Chems, and ECSD should fall into that category too. I actually bet you will find something more to your liking with Top Dawg then GreenThumb but I am not saying that is for sure.
As for an OG, instead of trying to find one that is exactly the same as a clone that you might have.. why not check out something new that could give you something slightly different but possibly better? Check out Bodhi's OG Crosses such as Goji OG, Sky Lotus, Lotus Larry, Cheech Wizzard, etc. Personally I'd give Goji a go, everyone loves her and I have never heard a bad thing about that strain. Have only grown one so far myself but it is a keeper. Very very potent stuff with many people having their phenos tested at over 25%. And it isn't like you have to search through 100's of seeds to find keepers either. You will probably find many keepers in a single pack.