"Can you reach 250 in a truly public thats always been state controlled?"
Yes.
"Does this also overide the inherent disadvantage in operations costs to which state controlled corps are subjeced?"
Govt-owned truly publics still pay higher fixed costs like regular state corps do. Remember also that with public corps, you only receive profit payments equal to the % of shares you own. So if you have a country-controlled truly public and you own 25% of the shares, you'll see 75% of the profits going out the window... unless there are taxes involved, in which case those are taken off before profit payments.