If you want to sell your final game...

A) The only way will be to contact Epic trying to get the license.
This is (imho) expensive or just not possible.
You may have to proove your quality by references at all.

B) Creating a similar shooter will be the better way (imho) but the audience - as you mentioned - can rate it (negative) as an old idea (with fresh technique/media).
But you could make a "sequel" adapting the whole gameplay (excactly) and change all media as well as the names and the story.
As I mentioned before add some fresh ideas (techniques) the crowdes can praise/talk about and advertise your game with a professional publisher.

I'm shure you will have success Frank.
The crowed can be impressed by cool graphics/lighting and this is yours.
Add some cool AI/shader/sounds/sountrack/cinematic camera in well designed levels (SP/MP) and you will find enough consumer...