Echlin #VC-1810 advance can or equilivant

How I determined what Cruise-Timing my 367 liked, was to drive on a flat, hard, level road, at a fixed throttle opening, NOT cruise controlled. Then,while driving I cranked cruise timing out of it. If the car slowed down I put the timing back in, and after it had recovered, I cranked some timing in. When the car picked up MPH, I knew I was on the right track.
If the road was long enough and level enough, or next time out, I added more cruise timing. I had to be consistent tho, always using the same stretch of road, and always with a fully warmed up engine, and usually in both directions, and on calm-wind days.
When I got really close, there was a plateau of about 4 to 6 degrees, with little or no change. I kept looking on that plateau for two summers, but improvement was hard to prove. In the end I ran on the bottom of the plateau, which I measured as 56*@60mph in direct gear, which was 2650 with 3.55s. And since then, 2004 or so, it's always been there.
With the overdrive now; 60=2070/65=2240, so she gets a lil less, probably about 51*@60 mph. My cylinder pressure is 177 to 180.