New Breaker, Receptacle, and Plug for New Appliance
Can't speak to if the frequency will be a problem, but 240V plus ground is a NEMA 6. Do not use a NEMA 10, it is two hots and a neutral. 

I don't believe a flash dryer operates at full current for 3+ hours, #10 and a 30A breaker should be fine, if it operates more than 3 hours at full current then #8 copper wire and a 40A breaker would be needed.

Edit: After good night's sleep and a cup of coffee I realized my answer at very least violated NEC 210.21 which limits cord connected loads on a 30A circuits to 24A, you would need to use #8 copper, a 40A breaker, and a NEMA 6-50 (or a NEMA 14-50 which would probably not satisfy a strict interpretation of (UL) Listing requirements of the cord cap to only install as the instructions describe and as tested by the testing agency, but (UL) is probably thrown out the window using a 50Hz appliance that has 50Hz sensors, timers or relays on 60Hz).