Earlier this year I got a chance to chronograph the Remington version of the much touted "FBI Load". l was under-whelmed.
From a 4" barreled 38 Special it averaged 804 fps, not the often quoted 900+ fps. I don't own a 2" 38 Special and neither does the guy I was shooting with so I don't know what it does out of a J-frame, except it's got to be way under 800 fps.
The very best 38 Special defensive load in my experience and opinion is the Buffalo Bore +P 38 Special 158g SWCHP-GC. When I choreographed that one from the same gun it averaged 1153 fps. That's almost an exact duplicate of your great grandpa's 38/44 load. (smile)