I am using blender.
It will likely be a few weeks perhaps a month before I am ready to start this part of the process at least with the bigger models. I have perhaps 250 hours into the 3D modeling and I will need perhaps another 100 hours, maybe more, to have the exterior and landing gear ready for UV mapping, texturing, bump mapping ...
I have factory blue prints for all (not some) of the external markings which are basically USAAF spec from 1942-1944 but with those specs applied to this specific aircraft model. Not sure off hand how many drawings this is but it is on the order of 10 to 15 sheets for the exterior IE. tons of accurate markings detail is possible. Plus I have drawings showing all of the panel lines and rivet locations on the wings, fuselage, doghouse.... It's a lot of work to dig through the drawing set to find specific drawings since there are over 11,000 drawings and these cover A, B,C, D, K and H models. But I am finding it is worth the effort to do since these provide a treasure trove of highly detailed information. In the end when you work from the factory blue prints you know that what you are producing is very accurate although it can sometimes be hard to figure out exactly what the drawings are telling you. If you are interested in helping with the texturing related stuff that would be great and I will start gathering up markings related drawings so I can get these to you. I spent about 4 hours this week doing nothing but locating and cataloging drawings for specific modeling tasks that need to be done.
I just put the finishing touches on the main landing gear legs on Tuesday and these could be textured at this point. The main landing gear wheels and tires are also done as is the doghouse. The main landing gear will not need bump mapping since every bolt, nut, fitting and protrusion is modeled. But these will need reflection mapping since the oleo piston is polished stainless steel but I do want to bump map the tread pattern into the tires. There are also markings in various places that would need to be incorporated into the main gear texture. In addition, I guess that it might be possible to start doing this work on things like the flaps, ailerons, horizontal and vertical stabs and the rudder and elevator and trims tabs for these. (I plan to animate all of the trim tabs and these are fully modeled at this point including exposed linkages) and landing gear doors. The wing is getting very close and I am currently working on the landing gear well details which is basically all that remains to be done for the wing 3D models.
There is also lots of 3D modeling that needs to be done on the fuselage and I have many of the drawings for these parts already cataloged so that they are easy to find. Most of these are smaller projects (for example. fuselage formers and longerons) that an experienced Blender user could model in short order. But there are lots of these that need to be modeled and for these simpler parts setting up the drawing for and in Blender is often more work than the actual modeling. Since the parts are relatively simple many of these modeling projects are suitable for less experienced modelers as long as they are willing to take their time and do a good job to produce an accurate model. On the other hand some of the needed models are going to be difficult projects that really need a more experienced modeler (the canopy and it's frame for example).
I have not pushed any of this to git yet but I will get things pushed this week end so you can have a look at what I have so far.
I have been documenting a lot of this work on the wiki so have a look at http://wiki.flightgear.org/North_American_P-51_Mustang for more information.
Longer term I am hoping to create liveries for this specific aircraft at different times in it's life. For example liveries for what it looked like when it left the factory in late 1944, on VE day, then various National Guard liveries from it's history, it's Soccer War paint scheme, it's Confederate Air Force colors and its present day colors (basically the same as the VE day livery). So 8 or 9 liveries that depict this plane through out its life. The factory and National Guard colors are mostly bare metal and silver paint (on the wings) and should be fairly easy to do once one of these is done.