I buy my blasting medium from Burrwell at Revesby.
i run a 4 cylinder diesel screw pump compressor. N 100 ltr hopper. Blast helmet n Breathing apparatus with filters.
those small blasters work but will take you a fair amount of time.
depending on how well the old paint adhered.
You will brobably need at least 100 psi constant for them to work well.
i bought my setup to blast my own project cars etc,
but I hate using it because it's messy, dusty, a drama to setup etc etc.
i wouldn't wish it on anyone, lol,?
Id just ring a local blaster if I were you.
and it would save you the hassle and mess,etc
cheers