Here's some information that I've gathered over the years from different sources and my own findings regarding all the variants of the 2.3 head. There are 12 different major head casting variations in the 2.3 engine. From the day of introduction, all lima based 2.3 heads shared the SAME valve diameters. These were 1.735 intake and 1.50 exhaust. The 2.0 ranger head can be easily identified by its much smaller valves and combustion chambers that match the smaller engine bore.
Head #1 ( Used 1974-75) Oval intake port, open D shaped chambers. Typical casting #s are D42E-AH/AJ/BJ and D4ZE-BC. Air injection holes in exhaust ports for the smog pump.
Head #2 Used in 1975-80 cars without turbos and 1977-80 courier trucks. Oval intake port, open D shaped chamber. Only change from the above head is the spark plug holes are tapped half way, which continued from 1975 and up. Typical casting numbers are D52E-AA/BA, D6EE-AA/BA, D7EE-CB, D8EE-CA, D9EE-AA/BA/JB/KB/KC.
Head #3 Used in 1979-81 cars WITH turbos (carb turbo mustangs). Oval port, D shaped open chamber. Same camshaft as the above, but did get heavier duty valve springs. Oil drain back for the turbo is IN THE HEAD, by the #4 spark plug. Casting #'s D9EE-JC, D9ZE-AA, E1ZE-AC.
Head #4 Used in 1981-83 cars WITHOUT turbos, 1983-84 cars WITH turbos, and 1981-82 courier trucks. This was the introduction of the "D" shaped intake port. The D shape was designed in an effort to reduce fuel puddling in the intake port during warm-up to pass emissions testing, which was a problem with the oval port design. Open D shaped combustion chambers. Casting #'s E1BE-AC/AD/CB/CC
Head #5 Used in 1984 cars WITHOUT turbos. This head is a D shaped intake port, but has a CLOSED (heart shaped) combustion chamber. This was the first year of this chamber design. The casting # for this head is E4ZE-DA.
Head #6 Used in 1982-85 cars using LPG fuel. It had hardened exhaust seats. The letter "P" is stamped on the back of the head. Casting #'s E1BE-AD and E4DZ-AA.
Head #7 Used on carbureted 1983-1985 Ranger trucks. (2.3) This is a very unique head from the rest, having 4 ROUND intake ports. The ports are roughly 1-7/16" diameter. Open, D shaped chamber. Casting #'s E27E-DA/EA.
Head #8 Used in 1985-88 cars WITHOUT turbos, and 1985-88 Rangers without roller cam. It has an additional hole tapped for the intake manifold in the #1 port. D shaped intake ports and closed heart shaped chamber. Casting #'s E59E-GB, E69E-AB.
Head #9 Used on 1985-88 cars WITH turbos. No air holes in exhaust ports. Open chambers, D shaped intake ports. Valvesprings are heavier and the exhaust valves are made of an inconel material to withstand the increased heat of the turbocharged engine. The most common casting # is E5ZE-EA/AB however there are more out there.
Head #10 Used on 87-88 Rangers WITH roller cam. Typical casting #'s E59E-GB, E69E-AB/FB
Head #11 Used on 1989-? Rangers and 91-? mustangs. The famed "Dual Plug" head, with 2 spark plugs per chamber. The first major redesign of the 2.3 lima head since the original pinto debut. Intake ports have a massive swirl dam in the bowl area to induce swirl for cleaner emissions and low speed torque. The intake ports are a smaller version of the "D" shape, however they are symmetrical as opposed to angled different directions like the early heads. The ports themselves are much smaller in diameter for high velocity low speed power. The intake bolt pattern is different from the early heads as well, manifolds will not interchange. The combustion chambers were redesigned as well for a higher swirl and faster burn. The exhaust port is identical however in location and bolt pattern. These heads all came with roller cams. No smog holes in the EX ports. Typical casting #'s E89E-AB, E97E-BA
Head #12 Used from 19??-?? in the Ford Ranger. Referred to as the "Late" Dual plug head, Ford's last shot at a cast iron 8 valve 4 cylinder head to keep up with the high technology coming out of Japan. It was similar in design to the above dual plug head, however the intake ports and combustion chambers were redesigned once again slightly. The intake and exhaust valve stem size was decreased to 7mm for a lighter valvetrain mass. The spring and retainer size was decreased as well for the same purpose. This head also had a multi-angle valve job that was done fairly well IMO.. This combination netted the best factory airflow numbers of all the 2.3 heads I have tested, however the potential of a true high performance head is very limited in my opinion and the older designs of the head have much more power potential given the same amount of modification.
There are some minute casting differences that can be seen with a good eye given the same overall configuration between 2 heads. There are some castings that have more material in some areas that will allow for more port modifications than other heads even though they are both "open chamber D port" heads. Some castings will outflow others in stock form, once again with the same overall physical characteristics to the naked eye.