Like I said early in the thread, and what Frank is telling you, get an Air Fuel ratio gauge and tune the engine so it doesn't stink. I cleaned mine up, it doesn't smell any worse then my '03 Toyota I drive everyday. Mine cruises at highway speed with a ratio in 15 to 16-1 range and around town in the 14 to 1 range. Before adding the gauge, it ran great and I thought all was good till I add the 02s and the gauge. I very quickly figured out it was in the 12-1 range most of the time, that explained why it smelled. I run dual Carter W-1 carburetors and still manage to get over 20 miles per gallon at 65 miles per hour. I could run a converter with no problems and probably would if I came across one for a decent price.
As far as the older '75 and up GM cars not melting converters down, I would guess the pellet type of converters used back then could handle way more abuse than the modern honeycomb type. I live up on a summit about 20 miles from down town Kansas City, I can still picture the yellow/brown fog that was over the city from all the smog so the addition of a converter doesn't bother me one bit.
