Mk1 Space Saver Flat

Just checked the original 95 space saver in my mk1 and unsurprisingly it's flat. I carry tyreweld, but suspect I should either pump up the spare, or bin it completely as it's bloody useless as is. I think from memory that these are meant to be pretty high pressure, like 60 PSI? Bit worried about pumping up an old tyre to high pressure - if a tyre lets go they can be lethal at close range - anyone any advice?