“positive swirl” combustion chamber

Makes me think the Nissan engineers were aware of that as it also showed up in the Z24i NAPS-Z.
NAPS-Z can be thought of as a 4 cyl, fuel injected, dual plug, emissions descendant of the Ball Stud Hemi,
rather than my assumption of the earlier engines.

sample quote

Note: All USDM gasoline Z20, Z22 and Z24 engines were known as NAPS-Z (NAPZ or NAPS-Z Nissan Anti-Pollution System), NAPZ motors had dual spark-plugs (two per cylinder) except the pre-82 versions and latest versions of the Z24i as fitted to the Pathfinder. All NAPZ engines sold in California reportedly had dual plug heads regardless of the year.

The fuel-injected version referenced above was denoted as the Z24i (Throttle Body Fuel Injection) and was first available in the Nissan Model 720 ST pickup during the 1985 model year and was replaced in 1990 by the KA24E engine and they share the same bellhousing pattern. Beside the fuel-injection, a significant change for the Z24i was the addition of an optical crank angle sensor in the distributor rather than a vacuum advance and ignition module. This allowed the JECS throttle-body injection system to identify the top dead center (TDC) of cylinder number one.

Engine Displacement: 2,389 cc (2.4 L) Bore x Stroke: 89 mm × 96 mm (3.50 in × 3.78 in) Compression Ratio: 8.3:1

When Bob Lutz said “No Hemi can meet emissions standards” the 5.7 engineers pulled out the SAE paper written by Nissan and he changed his mind”