240v outlets is a good start but main question that remains is how much power are they good for? Remember, today's miners all pull over 3kw each.
Two outlets each on a 20amp circuit should be okay.
Two outlets sharing a 30 amp circuit borderline
Two outlets sharing a 20amp circuit is a fail.
A 70th s17 is about 2900-3100 watts or 12-13 amps
two are 24-26 amps so they wont be able to share a 20amp and are borderline for a 30 amp circuit.
they do about 23000 to 25000 btus os heat.