>Model for the master and original clothing, the alien and few other things
>voice actors (there are forum fulls of them who probably have been fancy to fallout at one time or another)
>Creating the actual location and quests
>Adding the old fast travel system to the game.
You're going to need many more models than that. The Master's Cathedral, the Brotherhood of Steel tileset, the original Vault entrances, Shady Sands' buildings (Including the monument in the centre of town), Mariposa Base's tileset, the original Mutants models, the original centaurs, The Hub, Junktown's and Necropolis buildings, etc.
That is, unless you want the remake to look like Fallout 3 and New Vegas by using the same building assets.
Voice actors, good luck. Good voice actors are sparse. Especially if you want them to have as much depth as the originals for Aradesh, Tandy, Lou, the Master or the Overseer.
The originals have much, much more dialogue than the new titles...making your mod size huge with all the dialogue lines.
Creating the location is not a problem if you have the models. As you said, the locations are very small. But then, you have to program the schedule for every NPC.
Dialogue wise, again, good luck. The dialogue tree with the GECK and the originals doesn't work the same. Where as, in the originals it works more like a real dialogue between 2 persons, while in the new titles there's always a "let's talk about this" subject leading to sub-topics.
All in all, good luck!
By the way, I'm simply posting this to let you know how much of tremendous work it would be, not to deter you from doing it.
Oh and by the way, Hammer's scripting software is much much stronger then the GECK's.