Howdy Waldo and All:
As always, I seem to start with more questions. Does your 68/69 200 have the stock OEM distributor on those years? If so, it is not a LoM. It is a point type distributor, but it has centrifugal (Mechanical) advance and a vacuum advance that is sourced from a ports vacuum source in the carb. It is married to a Non-SCV 1100. In those years, pre-DuraSpark, FoMoCo was looking for better economy so down-sized the Autolite 1100 from 185 CFM to 150 CFM, and added the new (For then) distributor. Advertize CR also dropped from 9.2:1 '67 and earlier, to 8.8:1 in '68 -'70 (although we can find no physical dimension differences, effecting CR, in those years.
Q- "I was also wondering if I could simply replace the distributor to the 66/67 scv style and then hook everything up?"
A- Yes. When working as designed the SCV carb and LoM distributor work fairly well.
Adding a '67 and earlier 1100 to a '68 point style distributor, adds CFM, but the distributor advance will not work as designed. So on this forum have crutched the combo by sealing the SCV port and either increasing initial advance or running the LoM hooked to a manifold vacuum source, which usually requires less initial advance.
A better solution is to maintain your '68 style distributor and add a carb with a ported vacuum source, such as a 1101 from a '69 250 mustang, or a Carter YF from a '70 and later 200. Both will require minimal adapting, the 1101 is rated a 215 cfm. The Carter YF is rated at 187 CFM.
MPG- the first generation of the DuraSpark did not use points, but it had a small, point style distributor cap. From '68 to the early '70s FoMoCo used point type distributor that had both mechanical and vacuum advance from a ported source. It was replace by the first generation of the DuraSpark system, which later became DuraSpark II.
Petronix Ignitors are unique based on the shape of the top of the distributor shaft. If the top of the shaft is the same, all indications are that the ignitor unit is swapable.
Please share the details of which distributor you are using? Then we can get specific.
Adios, David