You will probably need to coat the 2 grommets with brake paste so that the reservoir seats properly. I have a tube of Permatex Synthetic Brake Lubricant #24127 that I use. You can coat the square oring between the MC and booster as well but it is not required.

Before power bleeding fill the reservoir to the top so you have a minimum of air trapped in the reservoir and the rear chamber gets filled. Make sure that the rubber seal caps on the level sensors are in good shape or you will have brake fluid squirting everywhere. Keep the garden hose handy for accidental spills.