Hi Deb, and welcome to Basenotes!
I love the original Halston and still wear the vintage stuff quite frequently. It has been reformulated and the change is noticable, but unfortunately, it's still the closest thing to the original that I've come across. The only thing I can recommend is trying to locate a vintage bottle or two - they still show up on eBay from time to time and you can tell the difference by the small script "Halston" written across the bottom of the bottle. The original doesn't have the signature.
Sorry I couldn't point you to something similar and still in production, but I hope this helps! Keep watching this thread though as someone else might know of a better solution for you - good luck!