Luckily, the only diesel we own is a GMC, and we try to stay away from the exhaust. We've been lucky that all of the fuel system has stayed sealed up. Neither my wife, nor I like the smell of diesel, which is kind of funny considering my wife is a master diver. Nothing will make her sick quicker than standing on the deck of a boat and getting a whiff of the exhaust fumes.
Our 79 is a 350 gas FI car. It came from a friend who bought it to install a late-model GM LS* engine in, but he found a 76 that was, amazingly, in better shape. It's one of the cars I've always wanted since they were new. This one runs very well, but I fear we'll be rebuilding the transmission soon (shudders going into 2nd gear and leaks some). I've already updated the sway bars and am considering new shocks, if I can get past removing the ride-leveling system.
Your Son's CTS sounds like a fun project, even if it needs some TLC.