You'll likely be able to advance the timing quite a bit past the ball & be OK. The timing was set up back then for a lot lower octane gas. I don't bother with the BB these days. I time to the fastest idle, retard a degree or two then fine tune using the octane selector. If it doesn't drag the starter or ping under load you're good to go.
This morning before the sun got to bright, for the truck will not fit into the garage, I hooked up my dad's old snap on timing light it says 6v & 12v on the back end, not inductive lead. That timing light gives off the brightest light I ever saw from any other timing light. Hooked up the Tachometer.
As you said there was drag on the start up. Well with the "O" painted white I was able to set it right on.
I also have the octane selector at 0 degrees.
Now the engine starts up very fast and with no drag at all any more, idles smooth at 500 RPM.
So the carburetor rebuild and tune up are now done.
