I just use permatex clear rtv, because i'm afraid if i used Ultra Black or the Right Stuff i would never get the main cap off again if i needed to for some reason.
Make sure when you fill the side cavities of the main cap that you keep going until you see the rtv squeeze out of the cracks between the cap and block, very important step.
Since i don't have to drive the car i let it sit for as long as i can before adding oil and starting the engine usually a week. But this is just my way of doing it and i don't have any leaks.