The casting looks good, hope your lungs look good as well.
I have never been successful casting with resin, but I just don't do it enough to be good. The resin would go bad before I needed it again.
Most of what I cast is small parts like that valve cover. Bondic would have made quick work of that with a few slush cast layers, all cured in 4 seconds. It's so good and quick at these little things.