Double Advent wiring question...

OK, here's to your original question. Yes, you can make a single run of speaker wire to each speaker and then add jumpers to go from the + of that speaker to the + of the stacked speaker, same for minus terminals (actually Advents labeled their terminals 8 ohm and 0 ohm IIRC). That is the appropriate way to do it. The reason I suggested running 14 gauge wire is that I assumed you were making a single run and using jumpers. I would make the jumpers out of high quality speaker wire (14 gauge is fine) and terminate the ends with spades. If you are going to experiment with turning the top speakers around make sure that your jumpers are long enough.  I would also suggest terminating the end of the long wire run with spades at the speaker end. I realize that this next point is outside the scope of your question but I would seriously consider replacing the speaker terminals in your amp with good quality 5-way binding posts. On most amps this isn't too difficult.

@8thnote........Perfect  and thank you.

Answered in a true audiophile fashion.

Too all others just enjoy your speakers!

About ten years ago I took my set of Large Advents (purchased in 1976 when then they first came out) to Van L Speakerworks and John not only re-coned my woofers but upgraded my internal wiring and cross-overs. They are not in my main system-I use them in my basement to play music when I am working out, hooked up to a vintage Sansui Receiver. It is a mistake imho to dismiss these speakers as outdated mid-fi. Granted, mine have been modded slightly but they sound awfully good and compare favorably to many modern era well-regarded speakers I have heard. The liveliness/snap/dynamics associated with rock'n'roll drums and the depth of the midrange is pretty exceptional. One of my favorite CD's to play while working out is The Ass Ponys' "Some Stupid with a Flare Gun" and on which the first and second songs contain some great snare drum/tom-tom sounds. The punch is exceptional through the Advents. 

I have a stacked set of 1974 Large Advents that I love the sound. I had the pleasure of knowing a design engineer at the Advent company and he told me to remove the foam inserts and fill with a certain amount of insulation, He also showed me how to re-inforce the cabinet inside with supports that really cut down the resonance inside them. I rebuilt the crossovers with quality parts along with the correct foam surrounds.

I have listened to a lot of $5000 pair modern speakers and my Advents beat the living tar out of them. When people hear my system they cant believe my 40 year plus speakers sound that good.

If you do it correctly vintage speakers can sound really good and you don't need to spend thousands of $$$$ to get good sounding speakers.

Don't listen to the audiophile BS that is spewed here by the ones that say vintage speakers cant compare to modern technology.  its nothing but lies.