I had a 660 and had trouble leaving strips of grass ( OK yard is weeds) where the
blade overlap was.
Dealer said mow slower and more often, but it didn't help.
Local surplus store sells EVERYTHING(Glenn's surplus in Shelby OH.) they
have mower blades including Gators now.
I got 2 sets of std. blades for a JD 72" mower,blades were 1/2" longer,but center hole
was close to 1" and mower has 5/8" bolts so I turned some bushings to adapt them.
It mowed lots better, Gators weren't around then.
So u might be able to do same thing, I found other blades the same style but they
were for other direction.
I was up to the surplus store the other day trying to get another set of Gator blades
for my 84" MMM (4 spindle) but they didn't have anything even close because of the
odd length.
They got Gator book out and it lists blades by length and by mower,if u have a dealer
close look at there book and if u have to get the Deere blades andmake or buy some bushings.
I hope u understood this mess
PS I really like the Gators on my mower,I was mowing some 3' tall weeds and all that came
out was small pcs.