That is absolute bullcrap rubbish. If he were to put a aftermarket catcon on the thing and check to see that the carb was not running rich then he would be no worse than most cars on the road today.
Most late 70's and early 80's carbureted vehicles that came out before engine computers were mandated for cars and that had catcons on them and EGR, are perfectly fine clean cars, as long as the engines themselves are still in good condition. The only ones of that era that really had a lot of problems later in life were the V8s. The engine computers and later fuel injection on the things didn't have much improvement until much later in the 90s when the engine blocks were all redesigned.
Ted