FuryDan66, The 67 - 68 Furys that I and my friends have worked on have required removing the windshield to remove the entire dash assembly. I suspect your 66 will also require removing the windshield to remove the entire dash. While the windshields have a gasket, the factory put sealant along the bottom edge of the gasket as it sits where the dash meets the cowl, essentially gluing the windshield gasket to the metal dash.
IMHO, if the dash pad is good, leave it and the dash assembly in place and remove the instrument cluster and glove box (if needed) to gain access to the wiring etc. (you will have to remove the instrument cluster anyway). Then remove the front seats for more room and do what you can do without removing the entire dash.