That is quite a generalization. An '83 Trek 400 has a nice lugged frame with butted Mangaloy tubing, which is pretty decent, and tried-and-true road geometry. It's a fine bike. Plenty of SSFG bikes produced now have Hi-Ten tubing with whack geometry and no cable stops of eyelets (obviously the Kilo TT being a great exception).

$400 could get you a pretty decent wheelset like you listed and some nicer brake levers/calipers with new cables, plus maybe an extra thing or two. You would have a great, reliable bike. Don't bother with the crankset, just get a 14 or 15 tooth cog to match with the 42 tooth chainring if you feel like 42 x 16 is too low of a gearing, which it probably isn't.