I have an MSD Digital 6 on my 82. I am currently using the distributor to trigger the box directly and have removed the Duraspark box. I bought the MSD harness that plugs into the dist plug. I have Taylor Spiro Pro wires.
I originally set it up using the Duraspark box to trigger the MSD, but decided to simplify. Not sure if you can trigger a 6 AL directly from the dist or if you need the Duraspark box. The directions should tell you, otherwise call MSD.
I am using the plain old Duraspark Dist, with the stock mechanical and vacuum advance and it works fine. I currently have the vac disconnected, but it works fine when I want to hook it up for street driving. I would stay with the Ford unit until you want to spend the xtra money for the MSD. That said, I would like to get one with a fully electronic advance setup vice the mechanical and vacuum stuff.
If you use the stock dist, the mechanical and vacuum advance should work just as well as stock, and you do not change them at all.
I've been using a 6al box, blaster 2 coil and duraspark box for years and with no trouble.
If I remember correctly, use the purple and green wires off the box. The green wire goes to the black/orange wire on the distributor, and the purple wire to the black/violet wire. Don't use the white.
They make a adapter so you don't have to any splicing.
Is there something wrong with your ignition?
The msd stuff will do absolutely nothing for performance, i'd make sure all stock parts are in good working order and if so, just leave them alone.
If they aren't, the most reliable ignition parts are ford motorcraft.
If you need new wires, just get the ford racing set.