Hi Techos, sorry it took so long for me to answer your question about the "standard" FAS Mustangs. FAS operated 6 P-51D Mustang (FAS 407, 408, 409, 410, 411 and 412) + 1 Cavalier P-51 750 (FAS 406), externally showing no difference to the standard Mustangs. None of these were equipped for combat when purchased from private owners in the US in July 1969, so they all were hastily armed and equipped in El Salvador.
They all were equipped with the standard P-51D canopy, so you can use the Tamiya-provided canopy without any problem (by the way, the Cavalier Mustang II did have a canopy very similar to the Dallas canopy, only with a slightly higher "hump" at the back, but notthing noticeable really).
Stock P-51D Mustangs used cuffed Hamilton Standard propellers, but it was not rare to see one using the uncuffed version of the Cavalier Mustang II as they were interchanged depending on availability.
Stock P-51D Mustangs were devoid of seat armour, and had no fuselage fuel tanks nor WWII vintage radios, so you can assemble a pretty nice empty space behind the pilot.
Bomb racks came from the Cavalier Mustang II, so they will be Light gray with the front end spareyed in Dark green, independaltly of the aircraft undersides.
As every stock P-51D paint scheme is unique, it is better to individualize which aircraft you want to assemble, most were painted a yellowish green (Khaki?) and Dark green with light gray undersides (like FAS 406, 407, 408, 409, there were three-colored (like FAS 402(II) late scheme and FAS 410), and Dark Green + Brown (FAS 402(II) early), you choose the one you want.
If you want to put some armament on those bomb racks, 100pd bombs is the only choice, there was nothing else to drop on the enemy back then...
Marco