Timing issues

I have, a used, unknown to me 340. Dial indicators, degree wheel; tells me it is 284; .484 lift, 108 centerline. 10.25 compression (70 340).
It won't idle under 30 degrees. I have talked to people, and read up on-line.
It seems the answer is; let the engine tell you what advance it wants at initial; if it starts with no kick-back, then pull the rest of the cent advance out of the dissy. I haven't gotten that far yet.