The EA52 was never sold in the US, and not much is interchangeable with later engines except for the EA62. See EA62 notes.
All EA61 and EA63 engines are 100% bolt-in swaps. They share most every part.
The EA62 found in the 1300G has rear exhaust ports (like a Type1 VW). It can replace EA61/EA63 engines if you reuse the front exhaust and make other minor mods. There are similarities but also lots of differences. These engines are the toughest of the 70s and the rarest and hardest to find parts for so it is not mentioned below.
The EA71 will replace all EA61/EA63 engines with little to no mods. Heads will not swap.
The EA71 will directly replace the EA81. Even though the EA71 heads are 1″ shorter, they will swap and raise your compression ratio to 9:1.
The EA81 will replace all engines with some mods, and is a direct replacement for the EA71. Every part will interchange, internally and externally but you have to watch out for year to year differences. Some parts like carbs might also require changing of the intake manifold.
The EA82 can replace most EA engines with mods to the frame rails because the SOHC engine is much wider. There are many other mods necessary and should not be performed by the ‘shadetree’ mechanic. The EA82 will NOT fit into an EA52/61/62 car, and will barely squeeze into an EA63 vehicle with heavy mods to the frame rail. This is a less common swap and is not mentioned below, contact us for serious details.
Also, watch out for EA82 cylinder heads, there are three: SPI/Carb are identical, then there are MPI and Turbo which are identical except for the extra oil and water ports on the turbo head. A non-turbo head can not be modified for OEM fittings, but the Turbo heads fittings can be blocked off for non-turbo use. Also, watch out for compression ratios and cams, the SPI/Carb heads have a 9:1 compression on a non-turbo block, and the Turbo/MPI heads offer an 8.7:1 compression on a non-turbo block or 7.7:1 on a Turbo block, (only difference is pistons). All non-turbo camshafts are identical year to year, and have a larger lift and duration than Turbo cams, good for a calculated 5-10hp on a stock Turbo motor. Finally, use of non-turbo pistons in a turbo motor WILL work perfectly, and is how I rebuild ALL of ours. This will give 130hp instead of the meager 111hp, the only drawback is you must either retard the timing or use premium fuel. Add non-turbo cams to that and you have close to 137hp! Cool!!!