Congratulation on your 78 SA. The First thing you should buy is the GM Shop Manual and the Assembly Manual and The Parts Manual and I have another one too. I got a 1978 also and if you ever need help on something I am willing to scan any pages of my manual and I will post it here... The common issues I had with mine was the rear end.. My differential yokes were loose meaning I was able to move them with no problem. I am replacing my whole rear end with new parts like a new leaf springs.. bushings.. new Strut rods, new struts...etc. I can be quite expensive especially if you buy from the states and you got some stupid duty fees.. Then I am restoring the interior.. and fixing my turn signal switch which it's needs to be replaced.. I can put my turn signal on but it doesn't turn off when you finished your turn.. Nice car by the way.. it's gorgeous..