You know the Original Fallout 2 Worldmap is 1400x1500, or 4x5 'WRLDMP##' FRMs, each 350x300 pixels.
A Worldmap that would include Fallout 1 locations, based upon
Lexx's design, is 2100x3000, or 6x10 FRMs. (Megamod presently uses a map that is 7x9.)
Modifying an actual satellite image of California/Nevada (maybe the same one Lexx found?) I was able to get all the Fallout 2 locations to line up nearly perfectly. (Sorry these are half size and blurry)
WM_N
As he and others have pointed out, Fallout 1 uses an entirely different scale than Fallout 2. To figure out where these locations should be, I enlarged part of a California map until a transparent diagram of the F1 locations would match when superimposed over it. (~ 300%)
WM_Cal
If we use the F2 locations for Military Base, Vault 13, Vault 15, and NCR/Shady Sands, then the F1 locations will match up almost exactly on the same grid and scale.
WM_S
Note the terrain of the road map for verification, and also compare the terrain of the
original Fallout 1 map. (Whoever wrote in the canon that Necropolis is what was left of Bakersfield was obviously mistaken. It's Barstow.)
Anyway, I lack the skills to paint in all the cities and details like Lexx did, so I won't go any further with it. But if you want the original full sized image (with no grid lines or cities) then PM or email me.