The only suggestion I have would be if you could find a Ranger, Bronco II, or Explorer with a 2.8, 2.9 or 4.0 and retrofit their ignition. You would have to do a little more research, but they are the same engine architecture IIRC so in theory they should swap with relative ease.
You can also just drop in a Duraspark II ignition from a '76-'78 II. You'd need the distributor (available inexpensively remanufactured via AutoZone), the ignition module (still available new), and the wiring harness (you can make your own if you need, it's only 6 wires total). Google "points to duraspark ii conversion."
You'd probably also want the distributor cap adapter, and larger more well-spaced cap (this was done to cut down arcing with the higher-energy Duraspark ignition). This would then also require new wires.
One thing to note, a lot of the Ranger / Bronco later-model 2.8L folks actually downgrade to the Duraspark II which works much better (especially if they're removing their VV carbs).
As this is a Mustang II, you probably know NOTHING is available as a kit! But I still love my II.
I just picked up a '74 Ghia V6 yesterday and found 3 ignition conversion kits at Rockauto -
AIRTEX / WELLS Part # 1A4141 {#ICC158}
Bosch Distributor; 12 Volt Negative Ground $95.79
STANDARD MOTOR PRODUCTS Part # LX809 Includes Wiring Connector; Modification Kit of Connector, Terminals, Harness & Bracket Supplied w/ the Sensor; Number of Terminals: 2; Number of Electrical Connectors: 2
w/ Single Points; Motorcraft $149.89
AIRTEX / WELLS Part # 1A4087 {#ICC104}
Motorcraft, Single Point Distributor; 12 Volt Negative Ground $150.00