I have a 8" Golden with a 4.5" russels lion and they get along great... Only thing you might want to watch out for is the puffer getting "tunnel vision" during feeding time. Best to feed the puffer on one end of the tank and the lion on the other. My lion takes food (silversides are his favorite) from my fingertips so once the puffer is busy mauling some mussels or something I feed the lion on the other end. He will learn the drill fast....
The puffers that are a problem with large lions are the Canthigaster genus puffers. The smaller puffers are notorious fin nippers and are small enough (not to mention toxic) to fit in the lion's mouth and are thus on the lion's menu. Bad combo....
Arothron genus puffers (Dogface, Mappa, Stars and Stripes, Striped, Panda, Stellatus, Guineafowl, etc) are usually okay with lions but monitor closely as there are always exceptions/trouble makers.
