From Jack Fitterer, bookbinder in Hillsdale, NY: It is possible to 'perfect bind' using PVA with a "cleat" reinforcement, and to round the spine as well:
Place the book in the laying press and cut a series of opposing diagonal slots across the spine at about 1'' intervals. Raise the book up in the press about half-way so the spine has some "air" in it. Apply a wide piece of tape over the spine to hold the pages in place temporarily (I use plastic package tape). Remove the book from the press and gently (!) round the spine into shape. Reinsert the book into the press, again about half-way, and fan out and apply the adhesive as usual. Lay aside under a light weight until dry. Finally, once again put the book in the press and glue a piece of thread into each slot, gluing down the frayed ends to the front and back of the text block under the area where the endpapers will be tipped on. Line up the spine as usual.
This method provides a "normal" book shape and securely holds the pages in place.