Yep, that's more or less correct. The B was at Inglewood and the C at Dallas. The C had the rear fuselage fuel tank as standard, and most B's had them retrofitted. You can build any B or C from the Tamiya or ICM 1/48th scale kits, you just need to check your refs for the particular aircraft being modelled, to see if it had the fuselage fuel tank filler. The Tamiya kit includes the later, 'Malcolm' hood, as well as the original side opening, framed cockpit canopy. I think the ICM kit does too, but can't confirm this. The old Monogram kit (now Revell) also has both hoods. The Tamiya kit has a slightly incorrect cockpit floor but, as most of it can't be seen, in this scale, who cares? Also, the prop blades are ever so slightly too 'thick', again not really noticeable, but can be corrected easily.
Here's a (rather poor) pic of my Tamiya P51B finished as a C of the 361st FG.