[Mike K]

I've pulled apart various speedos .. series 1 Land rover, Jeep, Morris Commercial ... to remove the needle .. I use a pair of scissors .. I carefully place the tips beneath the needle , at its hub , apply upward levering pressure

The needle flies off with some force , and I've lost a couple of them as it flew off somewhere .

That's interesting about Stewart Warner ... the contemporary Jeep gauges look similar, but are different apparently. SW was a GM owned company I think ? A Jeep ammeter would suffice as it's a generic instrument . Fuel gauge would be tricky ... has to be matched to the Chevy sender unit .
Mike