Ultimately, Plante edged McNeil by a 0.919 to 0.880 margin (granted that these are unofficial).
It also looks like McNeil's numbers were final (for the season) in the article above - and looks like Brewer's work has him with seven extra shots faced (and one fewer goal against).
I haven't gone through the game-by-game logs to reconcile the differences.
Every Wednesday the Gazette used to publish a stats package. From the start of the 1956-57 NHL season the goalie stats were called effifiency ratings(SV%) - see OP but by early March had reverted back to the old GAA format:
The disparity between Jacques Plante and his replacement Gerry McNeil is striking.
I guess it might be because Gerry had retired in 1954 after a pretty decent 3yrs with the Habs including that one glorious season & a Stanley Cup in 52 or 53 (?), having taken the torch from Bill Durnans' hands several seasons before. Some incredible performances along the way. Tough spot though. Just a little guy at 5'7" & 155lbs, inherits Durnans role but then along comes Plante & that was that for McNeil. He did however come out of retirement to play for the Montreal Royals in 55/56 of the QHL (followed by 56/57, then joined Rochester of the AHL for a couple of seasons followed by a year in the EPHL & final year back in the AHL in 61 before hanging them up for good) & when Plante came down with an asthma attack, McNeil was pressed into duty.... seems strange reading "Terry Sawchuk of the Bruins.... Glenn Hall in Detroit"...
^^^ Nice to see Charlie Hodge ranking in the #1 spot. Played 12 games for the Habs in 57/58, the rest of that season with the Royals of the QHL. One of my all time favorites. Tough spot to be in behind Plante however at just 5'6" & 150lbs, wouldve (and did) gotten worn down & out with a full schedule. At the IHL, AHL & QHL levels however before gaining a full time spot in eventually sharing duties with Worsley in Montreal, great little goalie & highly entertaining to watch.... post career he remained in Vancouver (Aldergrove) and became an Amateur Scout. About 20 years with Pittsburgh, 10+ with Tampa, and at 73 in 2007 still working albeit with limited travel. Quite the character & much beloved by his fellow Scouts and the target of a lot of good natured ribbing.
Little known fact is that he was also an Olympic caliber Canoeist (Doubles) who was refused entry to participate in the 1956 Summer Games as he was a paid professional athlete. Apparently still bothered him some 50yrs later, with veteran NJ Devils Amateur Scout Glen Dirk liking to often mischievously point out that Charlie couldnt swim, ergo he'd have been the only competitor in Olympic Canoeing history who wouldve had to have worn blow up water wings in order to compete anyway and who needs that? Game officials as well would sometimes deliberately mess with Hodges head in scrambling players numbers on the game roster sheets. Sometimes as well in Junior a call-up who wont be playing will participate in the pre-game warm-up & skate, just given a blank jersey, no number or name on it. This would apparently drive Charlie nuts, demanding to know everything about the kid, name, where he was born, where & with who he did play amateur from Tyke through Midget etc etc etc etc. Quite the stickler for detail, dead serious in apprising talent when the games started, always arriving to the arena 2hrs early and religiously eating exclusively at either Swiss Chalet's or Boston Pizza's when on the road.