That is a 8.0 to 1 compression engine so you can get away with a lot of timing, but 4 to 6 is a good place to start. HEI or points shouldn't matter on timing setting, both will fire the plug.
Just because its a '77 block and head, doesn't mean much. All the 250/292's used the same heads and had the same compression through the years, so the only real difference was the carburetors and how they were calibrated for each year of truck. The newer engines like yours would have more smog equipment installed and most likely a leaner burning fuel system, but the basic engine was the same as a '60s model.
Just set everything as a '65 and it will run just fine.
If there is any doubt about the balancer and markings, just set the timing where is runs the best, still starts, and doesn't ping under a load. Or if you are really concerned about it, get a solid stop and put it in #1 plug hole. Slowly turn the engine by hand till you hit the stop and mark the balancer. Then turn the engine the other direction till it hits again and mark that spot. Split the two marks and you have top dead center.
Joe
