Here's an update in case anyone is interested.
Since I started this thread, I got a new frame. Setting up the chain length, I ended up with these two configurations:
19T (for 64-65 gear inches)
17T (for 72-73 gear inches)
This was pretty unsatisfactory for me (even though I gather that its probably safe to do). I didn't have enough space for my winter tires if I removed an entire link from the chain so I went ahead and grabbed a half link. Here's the half link installed in my chain:
Half link installed in chain. (KMC half links on retrogression for cheap)
Here's how things worked out. Much better if you ask me! And still room for my tires.
17T with half link
19T with half link
As an aside, these wabi track ends perplex me
. There doesn't seem to be a way to utilize the inner 3rd of them without running into tire clearance issues with the seat tube, even with skinny tires.