OK, here's the sad story of the day.
I had a lead on a 68SD396 4speed, had a phone # to call last fall, and misplaced it. I found the number a couple of weeks ago, and called the guy tonight. The car sold 2 months ago.  The  seller said he only got a couple of calls, from NS, and nobody even came to look at the car!According to him, the bodywork was all done, just needed painting. Now I don't know if the 396 was the original engine, and I didn't ask.
There is a slight glimmer of hope. The buyer is relatively local to the seller, so I'm going to see if i can go look at the car and talk him out of it.