The HP24 is definitely beefier than the HP22, but almost strictly in the A clutch pack. Depending on the year of P38, the 4.6L torque converter is different (massive) as well. This was only on early 95-96 P38s and requires the matching flex plate.
Be careful with some of these backyard rebuilders that are popping up to fill a profitable market. Any clown can plastigage and replace main and rod bearings, re-hone cylinders, and replace rings. That is not a rebuild... more of a refresh...