Hi,
Authentic Decals produced decals for Lagg-3 (72-26) including some for type 66.
http://www.olimpmodelsgroup.com/olimp.files/Deka_LaGG_3_72.jpg
http://www.olimpmodelsgroup.com/olimp.files/Cover_LaGG_3.jpg
http://www.1001maquettes.fr/maquete-avion-toutes-marques/4927-lavochkin-lagg-3-sixteen-different-camouflage-schemes-and-markingst-1-72-decalques-avions-authentic-decals-7225.html
Here are the detailled scheme in color
http://scalemodels.ru/modules/forum/viewtopic_t_20060.html#
You can buy these decals here:
http://obchod.valka.cz/product_info.php?cPath=398_431027_431028&products_id=1063601&product_name=172-Lavochkin-LaGG-3