Since toe bellows are short for using short focal length (wide angle)lenses, you must add bellows to focus longer focal length lenses. If you are trying to use a 300mm lens on it you may run out of bellows extension before you achieve focus, especially if your subject is closer than infinity. I use a CC-400 and CC-401 with a recessed lens board for architecture, and do not have problems focusing on anything close as I have plenty of bellows travel, especially with the 401(22 inch bellows). You shouldn't have any problems using a 150mm lens for portraits with the 402. I read that someone uses a recessed lens board reversed (extension outward instead of inward)for longer lenses.
Congrats on the CC-402, its supposed to be a good camera. It uses softer bellows material than the 400 and 401 models for allowing decent movements with the shorter bellows draw.