Okay. You may have already known about this. Or you may not be as excited about it as I am. But...
I just found out that, in 1967, a "ferial Lectionary" was approved by the Vatican, which doesn't touch the traditional cycle of readings for the Old Rite (ie, the pericopes for Sundays, Feasts, Lenten Ferias, etc would all still be the same), but which gives a proper Lesson/Epistle and Gospel for all the ferias that didn't have their own previously and which just repeated Sunday's readings. On Third Class Feasts without their own lessons, one could either choose to use the ferial readings, or the usual readings from the Commons.
It was available not just in Latin, but in English too. In fact the English is all I can find, though as long as one has the readings you can always just look them up in a Vulgate for the Latin. I'll type up the verses that make up the cycle once I get it and post that here later.
The only annoying thing is that it gave "Series I" and "Series II" readings for the Epistles (though not the Gospels), which I don't like. Keep it to a definite, one-year cycle, I say. I would have much rather they had spent their time, instead of picking a second series of Epistle reading, simply picking a Prophecy/Old Testament reading to be a third reading each day (and restored the old Roman Prophecy cycle to Sundays and feasts). But, this is a good start.
Letting people choose between the Commons and the Ferial Readings on feasts is a bit odd too. I don't think their should be so many "options," that doesn't bode well for tradition (which involves internalizing a cycle which is the same and predictable from year to year). Rather, I'd have assigned the Common readings to the major prototypical Saint(s) from each Common category (of Abbots for Benedict, of Doctors for the Four Original Doctors and perhaps Aquinas, of Virgin Martyrs for those listed in the Canon, etc) and then specified the ferial readings for all the rest (which is still a lot).
I'm ordering a copy of this book, definitely, to study. I'd really like to try to tease out the logic behind their selections. The possibilities of real expansion and reform it offers the Old Rite, without having to touch the traditional cycle of pericopes (simply supplementing it)...are astonishing. I was actually thinking, for lectio purposes, of writing up my own "ferial lectionary" keyed to the Old Lectionary...but it looks like they've already done most of the work for me! Why start from scratch when their is already a "traditional" precedent to work with?
Ecclesia Dei has recently clarified (Deo Gratias) that the new calendar and lectionary cannot be mixed with the traditional rite. Of course not; the two are totally inimical in spirit. However, this 1967 Ferial Lectionary...might not be a bad idea to make optional. Someone should ask them about that...