The As 412 was an air-cooled H-24 with a 120 mm (4.7 in) bore and 130 mm (5.2 in) stroke. Total displacement was 35.3 L (2,153 cu in) and it had an output of 1,000 hp (745 kW) at 2,700 rpm. It was based on the As 12 (which was an H-16) from 1935.
The As 413 was a water-cooled H-24 with reduction gearing for contra-props. Output was 4,000 hp (2,983 kW). It may have run, or perhaps was scheduled to run, in 1945. I believe is did use cylinder blocks and other parts from the Jumo 213. If we assume it had the same bore and stroke (150/165 mm, 5.9/6.5 in) as the Jumo 213, then total displacement would be 70 L (4,270 cu in). That seems reasonable with the output.
As far as I can tell, Argus also designed two other air-cooled H-24 engines, the As 14 and As 403. The water-cooled As 404 was most likely an H-24 too. None of these engines were built. The As 403 had single cylinder test engines built, but it was passed over in favor of the As 413. The As 403 was to displace 64 L (3,905 cu in) and produce around 3,500 hp.