Wow, that just makes things even worse not getting any of the parts back. At least he does not have physical possession of the car anymore. Such a terrible outcome on this one. I sure hope they got the keys and it will run without much effort. Sooner you have it back, sooner you can regroup and know what direction to go. It took me years to save as well when I did mine so I can really relate to that.
For $10K, do you think it's worth the expense to file a small claims suit against him? $10K is right at the small claims limit and if you can get a quick judgment, the sooner you may see something if you can put a lean against his stuff as everyone else is no doubt before it's all liquidated and split between those involved.
http://www.TheFOAT.com/92GTA 1969 Pontiac Firebird w/BP 461ci stroker kit, 670 heads & XE274H cam. Primer black with black interior. 1992 Pontiac Trans Am GTA w/SLP Performance Package. Dark Jade Grey Metallic, grey leather, T-Tops.