So as to not be burned at the stake by Campy aficionados in the group, let me preface my views about Campy rear derailleurs: I share the experiences and opinions that Frank Berto outlined in his book "The Dancing Chain".
Back in the early 70s Suntour rear derailleurs worked very well but they looked like cheap $6 to $8 products compared to Campy NR derailleurs. Like many others cyclists during those years, I too looked down my nose at the "Cheap" Suntour derailleurs.
In 1975 I got one of the first sets of Suntour Cyclone derailleurs to come on the market. The finish was excellent, the price was affordable and most importantly they shifted far better than any Campy rear derailleurs of the day.
Campy derailleurs worked well on 14T to 18T "corncob" freewheels but beyond that they lacked crisp shifting. The Cyclone could handle up to a 26T large rear sprocket smoothly.
In 1975 I also switched to 49T-45T front chainrings for 1/2 step gearing. At the same time I went from Campy NR to Stronglight 93 cranks because they shifted smoother and I could use a 38T small chain ring if needed instead of being limited to a 42T.
These days, 49-45 chainrings with a 13-26T freewheel is still OK for flat rides but there are too many hills around where I ride so I need bigger gears. I'm using 48, 49 or 50T - 38 or 39T cranksets with 13-28 freewheels.
I'm just finishing putting together a 1984? KOF Holdsworth Reynolds 753 with mostly Campy SR components. I'm using a Campy Victory crankset because I was hoping to use 50-35T "compact" chainrings with a Sachs Aris 13-28 7 speed freewheel. I have a second generation Super Record rear derailleur which is rated at 28T FW capacity. This evening I had to give in and switch to a 38T small sprocket. The SR derailleur doesn't have enough chain wrap for the 35T sprocket.
To respond to your questions about rear derailleurs, most of the Suntour long arm derailleurs from the 70s and early 80s work very well. The long arm Cyclone derailleurs are a little flimsy.
I recently acquired an all original 1971 Hetchins Italia with an all steel Suntour long arm rear derailleur. I was told "Alf didn't like the Campy Gran Turismo derailleurs and this was his answer".
In my opinion the Shimano long arm Crane and the lower priced Titlist derailleurs work slightly better than the early Suntour derailleurs.
Now to the French derailleurs: the steel Huret Duopar derailleurs are still hard to beat for wide range touring gears. The steel bodied Duopars are a little more rigid than the titanium ones. They will handle a shift from a 13T to a 34T sprocket in a single move better than any indexable rig running a tricked out close pitch 8, 9 or 10 speed cassette and chain.
There were some later model Huret/Sachs derailleurs that came out in the 80s that were Shimano knockoffs.
Many Simplex models work very well. I assembled 100s of French bikes with Simplex Prestige derailleurs during the Bike Boom. Those bikes came with 14-28T freewheels and 52-42T, 52-40T or 52-36T chainrings. With a little tweaking the Prestige derailleurs could handle all of those combinations. Many times you could even go to a 30T freewheel.
I'm not saying that I liked the cheap plastic Simplex derailleurs but when new, well lubed and properly adjusted, they outperformed Campy rear derailleurs. The later alloy Super LJ and similar short arm models were very good. I have them on a number of bikes including one short arm SLJ that's running a 13-32T freewheel with no problem.
The long arm Simplex metal derailleurs are excellent too, especially the ones with Shimano style parallelograms.
Get one of the newer style chains. I like the SRAM PC-850 6/7/8 speed chains.
Oakland, CA USA