22.4% of your voting power is from your old steem.
But anyways 13.44*.7759....=10.418
If the cost of leasing the 300sp was $9.6
your profit might be .81.
Not much room for mistakes, and steem prices varies greatly. The other thing is if you vote for yourself superlatively, other users won't like you-and some steem users throw a fit about those who do. The other thing is, if you are voting for yourself, you aren't voting to advance your rankings as a top user in steemfollower-which is how I found your post.
In Regards Of Upvoting Myself, I Won't Be Upvoting Any Of My Own Comments, I Am Using The steemfollower.com Exchange So That I Can Give Back To The Community And Get Rewards In Return :)
That was also my idea, upvote others on steemfollower and the upvotes will come back.