What's the part number for the chip?
Have you asked other VK'ers? Among us, we have one heckuva stash of parts. I personally have over 300 NOS NAP packaged parts, and a few dozen "chip" kits for various Sylvania/Philco-Ford sets. Don't give up - get resourceful!
And yes, I have several of the supposedly unobtanium vert/horiz countdown chips - ECG792 and 793 equivalents.
I posted long ago in AK aboout creating a "resource" thread where we could list our parts stengths - several posted in favor of it, but no moderators weighed in.
Cheers,