Good effort beast! Although I agree with Chris- it looks at least 7c. Is it a true sitter or just a low start?
Considering Black Jumper involves a jump start, I'd suggest a nice low start is the true way. It's not like somebody has climbed a sit start to West Side Story, now is it?
eeer, i think you shall find that"West side story" was originaly climbed and graded as a route, to the top!