Howdy Pony and All:
If your goal is to maintain a stock appearance then FYI- FoMoCo used a point type distributor with both centrifugal and vacuum advance beginning in the 1968 model year. It was used in conjunction with a downsized 1100 which had no SCV but a ported vacuum source for the "New" distributor. Some of these distributors used a vacuum cannister with both vacuum advance and retard. If you can find one with only vacuum advance that will be cleaner in appearance. If you have to use the advance/retard cannister just don't use the inner nipple on the cannister. Don't plug it either.
The first generation of the DuraSpark system began to appear sometime in the '72 model year (IIRC). It is a pointless distributor with a remote module, and a specific coil. It has a small black cap and early type spark plug wires. It used both vacuum and centrifugal advance. If stock appearing is your goal along with better performance and lower maintainance, then this is the way to go. I would suggust that you invest in some better spark plug wires as the OEM carbon impregnated core wires are prone to leaking and shorting. Spiral wound solid core wires are the way to go. Some shorting inside the small, stock appearing distributor cap is also possible, so keep in clean.
The next and last generation of the DuraSpark system was called the DuraSpark II. Clever huh? It begin to appear in the 1974 model year and remained until the distributor ignitions were replaced. The biggest difference between the DuraSpark and the DuraSpark II was the size of the distributor cap and larger diameter spark plug wires. There were also some specific changes to the module over time and applications, but that's another story.
Both the '68 & '69 point distributors and the early DuraSpark will be compatible with your RBS carb. What head are you using. FYI- the carb bore on the '66 head will have to be modified to allow the butterfly valve of the RBS to open. If stock appearing is the goal, I'd recommend the Early DuraSpark system. Open the plug gaps to .045" or .050" and never have to adjust the points again. Keep us posted on your progress.
Adios, david
