273 auto trying to find the 'tick'

Check the flex-plate closely for cracks. Drop it on the cement floor; if it sounds funny, check it again.

At idle, for testing purposes, you can put anything on the crank that puts the ring-gear in the right spot; but a bellhouse bolted on would sure be handy. When the starter whacks the ring-gear it takes a lot of torque to get her moving, applied in a very short period of time. if you build something (a waste of time IMO if you already have a BH sitting there), it better be strooong.