Not sure if your looking to replicate the actual theme from your HTML site and make it the same as wordpress, but when I was ready to take the plunge from HTML to Wordpress, all I did was find a theme that I knew had good success with CTR and such for Adsense, copied all of my content and then changed the permalinks to end in .html so I wouldn't have to worry about re-indexing and such.
I experienced no complications this way, and actually ended up getting better CTR with the new theme. I was hesitant at first to do this because I didn't want to lose the money I was already making. Turns out it increased, so I am happy I did this.
I no longer have the website in question, but I believe you change the permalinks to %postname%.html or something like that. I am sure if you Google it, you can find what you need.
This was the easiest thing in my opinion. Other then that, I am not sure.
Hope that helps man.