diff is still the same as % of hash to found the block 6000 , i think 1 ph will be good
then you will have 20 mil difficulty, 100 TH would be better !
The thing will have to be nursed lower, if you throw a lot at it then either the rigs or the stratum needs to be switched off as soon as the block is found and then turn off the rigs and turn on stratum and see what the next block diff is to know what to throw at it.
Alternatively just wait it out with what is currently available.