Any good acrylic masonry sealer should work. The only problem will be that some remaining wallpaper might come loose after applying the sealer. In this case, pick off the loose wallpaper and keep applying the sealer.
The water based masonry sealers are quite good for this application and won't smell really bad, like oil based products. Plus you will have a choice of sheen. Usually satin or gloss with gloss being the "wet look".