For better detailing, you'll want to paint most parts separately, then remove paint as necessary to glue and assemble them, which it looks like you've figured out on your engine. There's always exceptions, and if you have questions about how something should look, use Bing images (or some other search engine) for research.
It looks like you have the carburetor mounted on it's side. Look at the instructions closely and see if you can tell how it should be installed. Unfortunately, the part drawings in kit instructions are usually not very detailed, so it's easy to install something incorrectly if you don't know how it should look already. Here's a pic of a big block in a '69 Camaro to give you an idea of how the carb mounts.