If you unplug the selector box, it defaults to curve 4, which on a untouched Dynatek is the "stock" curve.
If you go +4* on the plate, then you'll end up at 17* from 10-12K. This may or may not be too much timing. You may be better off just buying a programming cable, maybe only turning your plate +3*, using curve 3 with plate at 0*, or swapping ignitions with somebody.