Parmandur
Book-Friend, he/him
I owned Forgotten Temple back in the day, and I remember it as an absolutely awful module. One big fight and then nothing but mopping up. The pacing was atrocious. But, then again, that might just be my memory playing tricks.
I'm not sure that focusing on Drow would be a good way to go. I think that Forgotten Realms have pretty much sucked that idea dry. Even the idea of redoing the old GH Drow city isn't really going to distinguish it too much from FR. Yes, I KNOW there are differences, but, I'm not sure if the perception of those differences would be enough. It's an underground city matriarchy led by dominatrix dark elves. That's an idea that really has been beaten to death.
I'd suggest that focusing on stuff that you don't see in FR might be a better way to go. The Paizo Dungeon adventures - Seeds of Sehan for example - with its body horror, use of somewhat more esoteric monsters (yak folk monks?) might be a better direction. Play to GH's strengths rather than try to directly compete.
There was one book released in 2016, years ago, that didn't primarily focus on the Drow. Like NBC used to say, even a repeat can be New.