Here are the models from the 1970's in ascending order of quality:
Model 58, 68, 64: Junior Racer, smaller frames and wheels
Model 70, 71: Black Diamond, seamed tubes
Model 74: E.C., seamed tubes
Model 82: Super Tourist, seamed tubes
Model 88, 89: Super Tourist Deluxe, Reynolds 531 plain gauge seamless
Model 80: San Remo Cote d'Azure, Reynolds 531 plain gauge seamless
Model 78: Olympic, Reynolds 531 plain gauge seamless
Model 92: Super Route, Reynolds 531 plain gauge seamless
Model 90, 94: San Remo, Reynolds 531 double butted
Model 96, 98: San Remo, Track Bike, Reynolds 531 double butted
Model 76: San Remo, (aka Equipe or Professional) Campagnolo NR, Reynolds 531 double butted
To make your life complicated the model number is not on the bike and only sometimes is the name there, usually on the chainstays. Early 70's models came with European components like Simplex, Campy, steel cottered cranks and aluminum rims. By the mid 70's Ernie was using more aluminum cotterless cranks like the Maxy and was using Shimano derailleurs by the late 70's.
During the bike boom of the early 70's the Black Diamond competed head to head with Peugeot UO8 and Raleigh Grand Prix in price (about $125 in 1974). Because Falcon had gone to cotterless cranks and aluminum rims earlier than its competitors it had that edge. My memory is not infaliable and if any of this needs correction please someone jump in. These were all great bikes and to have that kind of choice was great for a teenager with a wad of paper route money burning a hole in his pocket.
Any of the bikes with 531 tubing are pretty nice. Lots of room for real-man size tires and fenders. The Model 76 came with chrome headlugs, Nervex professional or plain Prugnant, and all Campy NR with Campy brakes on the racing model and Weinmann centerpulls on the road model.
I recently bought a Super Route and it weighs 25 lbs with 27 1 1/4" tires and water bottles. Light enough for me then and now. I think they're a great value but then again I think that's true of a lot of imported bikes from the 70's and 80's. For a couple hundred dollars you can set yourself up with a bike that is as good as anything costing $1,000 or more in a bike shop today and it will be a lot better looking.