Gargoyle
Adventurer
I did almost the same thing with the FR game I'm running currently except instead of 3.5 I'm using the Pathfinder rules. When we officially move to D&D 5th I'm still undecided a whether to advance the time or just set in the same time as my current game. I have quite a bit of FR material starting from the gray box set to the 4th Edition FR books.
Also if I recall correctly from the original box set I believe that Sembia and Impiltur were left undetailed so that a DM could flesh it out themselves.
I do remember that. Not sure how long that lasted. Guess they just couldn't help themselves as every corner of the setting seems mapped out and novelized.