I just did this job, and I used brake cleaner on many surfaces. However be aware that brake cleaner DID swell the black factory sealant between the lower and upper portions of the block. I was very concerned but so far so good.Same question goes for the top of the heads. It's not too bad in there, but I do need to clean it up some. If I flip the engine upside down so nothing will flow down into the oil passages, am I safe to use brake cleaner there?
For this reason I would NOT use brake cleaner except on surfaces such as the timing cover (get new seal) and the valve covers.
BTW on my valve covers, the baffles were riveted in place. I didn't remove mine; rather, I soaked them in hot degreaser and then swished them out with carb cleaner. Just make sure the drip holes are clear.