Is it possible to replace a 1979 dash with a 1970-1978 dash ? Are parts all available if I make this change? Thanks.

From what I have seen it's an easy swap, if you're looking for parts I suggest checking out NastyZ28.

http://www.nastyz28.com/forum/forumdisplay.php?f=13

You will need the 70-78 dash pad and outer gauge bezel. You can use 79-81 gauges, but will need to change the lens, or at least modify the one that you have by removing the turn signal "spikes". Not sure if the ductwork is the same or not??