Center height of headlamps for 28-29 is 37-5/8", 30-31 is 38-11/16", which accounts for some of the difference. Also H-type and TwoLite use different bulbs, as 1930 coupe says.
http://www.motormayhem.net/model-a-f...pecifications/
In either case the lamps will have a slight downward tilt. Proper focus should produce an 8" diameter bright spot (without lens), regardless of distance.