You wrote:
"That means the post rewards would need to be the approximate equivalent of 65-70 SBD per contest post."
But what you meant is $65 per post instead of 65 SBD per post. That gives a whole kind of different calculation. Basically the one you explained to me.
However at this moment there is a detail that causes a little twitch. Part of the SBD pay out is done in liquid Steem. So without calculating it I'm 100% certain you need a higher average post pay out to reach the 250 SBD goal.
Now I make my next assumption, I think the SP+liquid Steem pay out is what you earn, correct?
If so that would mean you end up with 26/1.7=15.29SP on average per post. Multiplied with 13 gives 199 SP. Add up 25% (currently it's above 30%) for liquid Steem pay out and you can earn close to 250 Steem.
It's really remarkable that you can pull this off. I have to hang around 2.5 years on Steemit to earn such an amount.
Btw, don't get me wrong by thinking I disagree that you should earn this. I just like numbers and investigation as I am an economist. So keep up the good work!