The ultimate solution to locked distributors, crank triggers, etc (when using an advance curve is not viable) is to use an additional pickup in the distributor. Install the second pickup so that it will retard the timing about 20 degrees compared to the crank trigger pickup (or primary pickup in the distributor). Start the engine on the pickup that is retarded 20 degrees and then once the engine is running, use a dash mounted switch to switch over to the primary pickup. This eliminates advance curves and start retards but still allows full advance at idle speeds without risking kickback.