I am putting a 2.3 in an 1953 Willy's and am told that basically all the 2.3 heads are interchangeable but that the block changed in 1974 or 1975 ?
The change was in 1974. 1974 -1984 2.3 are the same. then the heads were changed a bit to accompany the start of fuel injection. Even some of the 2.0 engine heads will interchange with the 2.3 but they have smaller valves so I wouldn't recommend it. The short blocks are basically the same from 1974-1994.