Well "release lube" overnite, then the dreaded "Mapgas", fuel lines only 25 ~ 40mm away (its OK the cars insured), a good heat up, later the bolt gives up, and whilst it turns and unscrews from the block, it wont come out of the pump, pump now off, pulley off pump, heater spigot seized, I think it best to get a new spigot for the new pump. Its annoying they dont supply the pump C/w spigot.
O B one, please dont feed leading lines like that to Bfit, he's likely to come back with something about "the enormity" of his situation.