Sandblasting question

Buy a regulator and try different pressures. I would start with 70 PSI.
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Depends what you are blasting, and what media you are using. Blasting cast with sand you can use up to 120psi - blasting aluminum sheet with plastic media or walnet shells 50psi might be too much.

What are you blasting? What size and type of nozzle? Pressure or siphon feed? What media will you be using?
Heavy rusted steel using Black Majic will take 90-100 psi 10 CFM or more with a small nozzle. 33 gallons might last you 30 seconds or so unless the blaster is a tiny siphon flow one.

I have a Sears sandbaster from the 1970's that holds the sand in a pressurized screw-on cup. Its max rating is 50PSI. jsw

Buy a regulator of a larger size than you air line so it isn't a choke point, i.e. get a 3/4" regulator or better.

Anyone wanting to get objective opinions/advice for this sort of situation should get pictures to show both the air compressor and the sandblaster.
A typical home shop 2 cylinder single-stage compressor (in very good working condition) can only support a pressure feed sand wand/gun tip orifice of about 1/8".. even then, there will likely need to be numerous pauses for the compressor to catch up.
Sandblasting uses a lot of electrical energy for the work performed.. it's much more cost effective to use paint strippers, wire brush, acid or scraping methods to remove the majority of paint, rust or other contamination, then use sandblasting only for deep pitted rust. Some commercial corrosion prevention paints are surprisingly resistant to sandblasting.
The concentration of the amount of abrasive in the air stream is a significant factor when it comes to efficiency.. a mixer valve on a pressure feed sandblaster needs to be adjusted when blasting media types or air pressures are changed.

It can be set up either way by moving a setscrew plug. jsw