Well, you're on the right track... it's better to use a heat gun and get the block pretty warm. A hair dryer just won't get it warm enough. Also, if I remember correctly (someone jump in here if you have broken in an OS 12 more recently than I) you should have leaned the hi needle at leat 1/2 turn and the low needle a 1/4 turn before ever trying to start he motor. The stock settings are so rich you can't even keep the motor running. Then bench tune the motor making sure it stays below 200deg F at idle. The hi needle should be lean enough the motor doesn't try to die when you snap the throttle but rich enough it doesn't want to scream.

Make sure the piston isn't on TDC when you kill the motor before it cools off.

Now take it to the track and run it like you are racing but don't necc. try to run full on punched. Make 2-3 min runs to get the motor good and warm keeping an eye on plug temps. I wouldn't let the motor get over 230-240deg. The reason for 2-3 min runs is to heat cycle it so let it cool 10-15 mins between runs. After 4 or 5 heat cycles begin to tune the motor for full HP being conservative with your increments. It's much better to sneak up on the tune than miss it and overheat the motor.

DO NOT waste your time with all that 2 tanks at rich idle, 2 tanks at kinda rich idle crap. All it does is hurt the life of the motor and cause an incorrect piston/sleeve mating.

If the motor gets stuck on TDC on the starter box, just use a small flat blade screw driver on the flywheel to kick it past. You might also try hooking up your 12V charger to the battery in the starter box to give it an extra kick. An SLA battery normally has about 12.8V at full charge but if you hook up the charger you will be getting 13.5V (slow charger) to 14.5V (good charger) which will help. If you're using a doubble stick pack then make sure the packs are fully charged.