Yes, I thought the same about the seat.
I have one of these seats, but I mounted it on a fibre glass base so it sits an inch higher at the front, and higher still at the back. I find it surprisingly comfortable, though Andy Nixon's special padding makes a big difference.
This photo exaggerates the seat somewhat, and it doesn't look this angled from other views:
If you just mount the seat on top (back) of the frame pressing, it leans back, making the distance to the handlebars greater. As a result, you have to lean forward to reach the bars, giving you backache.
Good luck with therest of the project. What are you doing with the paint?