Original Pignose 5 inch speaker load???

[J M Fahey]

I ran it into an 8 ohm load and it puts out around 1W RMS before clipping. Not sure where they got 5W from

Easy. They were pioneers in many areas.
Probably were rated 5W P.N.P.O. (Pig Nose Presumed Output)
Seriously, 5W RMS would have been LOUD, and would kave killed those 6 AA's in 15 minutes.
My own version from the 70's used a no transformer, but a conventional totem-pole output , with germanium AC187/188 transistors, straight from the Philips datasheet, powered by 6 "C" batteries, and sported a high gain preamp (the Pignose just runs straight into the power amp) which gave it huge sustain.
In Argentina it was much preferred over the original one, and was used by some of the best guitarists to record what later became gold records.
Even today it's fondly remembered in magazine articles.
I had to stop making them when I ran out of germanium output transistors.
The silicon version, with Tip31/32 was a fiasco, dry and farty.