I don't know whom you are referring to, but I said something along the lines of 'a pegasus is LIKE an underwound custom 5'. Meaning: same magnetic structure, same wire gauge. but I have no idea about the wind pattern or wire insulation. If a Custom5 has 43 formvar and the pegasus has 43 plain enamel, even if they were to have the same amount of winds and DCR, the tone would be immensely different.
There are in my view, a few custom-series derivatives:
Pegasus - Alnico V - 12.5K
Nazgul - Ceramic - 13.6K
Screaming Demon - Alnico V - 10.1K
SH6N - Double thick ceramic - 13K
Perpetual Burn - Alnico V - 12.1K
they all have 43 awg wire, all the same baseplate (and with the exception of the SD) same polepieces. But the exact wire/wind specs, I do not know. All of these sound quite different from one another but I wouldn't be surprised if, for example, the Perpetual Burn is like the Pegasus, but has a totally different insulation (say, heavy formvar on the Perpetual Burn and Plain enamel on the Pegasus).