Will also give this tid bit. Almost none of my engines are under 12* of timing anywhere in the timing map and some have as much as 20* as the LEAST amount of timing in the whole graph. Even stock cam engines often have zero issues with what I will call initial timing at 16* aka the lowest value in the MAP. I cannot tell you how many of those old 260 HP GM Crate 350s that I woke up drastically by recurving the distributor and welding up the slots to limit the total advance with the new advanced timing. I would shoot for 18* initial, 18* centrifical (36* total) and 10* vacuum advance on those engines. I am confident enough in it that I will say any value less than 12* in the timing map, make 12* and see what happens. If it likes it go 14*, if it still responds without tip-in knock, go 16*, etc.