Oh man, this is a classic AD&D adventure! One of my personal favorites along with Against the Cult of the Reptile God and White Plume Mountain.
I have Savage Worlds Deluxe which I believe they are now calling the Explorer's edition. Are there any significant differences in the system that would justify my purchasing the new (unfinished) Adventure edition or would I be okay just going with what I already have?
Savage Worlds Deluxe should be fine. There are a few minor differences when it comes to character creation, but those mostly have to do with the skills being reshuffled, and can easily be explained.
You state that the module is one of your favorites. Does that mean you've played it before?
Yes, I played it when it first came out in the 80's, so it's been 30+ years. I still remember the general theme of the adventure but not much of the nitty-gritty details.