Hecateus--
Welcome! There is a very generalized map of the Third Imperrium's 'charted space' in the GURPS Traveller book, in
Library Data A-M and
Library Data N-Z, both available in the Supplements reprint from FFE and (goes and checks book..) in the Book 0-8 reprint.
The Core is usually 'north' on Traveller maps, with 'south' being rimward and 'west' being spinward. Given the scale of Traveller's 'charted space' the actual core is some fourty or so sectors off the top of the map.
Most local stuff is in the Solomani Rim sector - I believe Chris Trash has a table on his website as to which stars in the Solomani Rim correspond to which 'real' stars.
Deneb is in the Deneb Sector, Antares in in the Antares sector and Spica is in the... you guessed it... Spica Sector. The Pleides are three or four sectors rimward of the Solomani Rim sector. The Coal Sack would be two or three sectors 'north northeast' of the Solomani Rim sector. Probably out past Crucis Margin somewhere. I doubt it's astrographically worth mentioning on the sector map concerned.
The Magellenic clouds are so far off map as to be completely irrelavent. It's a BIG galaxy and those clouds are outside of it. On the grand scale of things a couple hundred parsecs really isn't all that far.
And YES - squashing a full dimension out of things certianly causes some distortion - but then there's that whole silly notion of playability.
Still, Traveller gives a much stronger nod to astrography and astrophysics than certian wildly popular 'science fiction' franchises in movies and television that I could name... but then you *DO* have to (at least) be able to read and add dice pips together to play Traveller
HTH
--Michael