Being the gear nerd I am, I learned that in 1988 Marshall made a limited number of 1959 and 1987 NMV Heads as the first Plexi reissue. They copied the transformers of a particular pair of 1972 100/50w transformers and circuit values and that is what those amps were based from. The headshell front corners have a inside curve where the faceplate ends on both sides; that's a tell on those amps.
When Marshall officially reissued the Plexi as a production (not limited) model in 93/94 they used those same transformers until they were used up; sometime in the late 90s but maybe they lingered longer. So this Hendrix head has those same exact copies of the 1972 100w that they blueprinted. I know certain modders who highly recommend these early Plexi reissues as being equal to the metal panels of the 70s.
Killer amps.