Lower Unit Gears in 1954 Evinrude Fleetwin 7.5hp

[vg569]

My 54 Evinrude Fleetwin 7.5hp outboard shows model number 7516-31016. I went to rebuild the lower unit which was seized. When I ordered replacement used reverse and forward gears and reverse bushing, the gears that came had fewer teeth and didn't mesh with my pinion drive gear. Were there two different gear ratios offered on this outboard or did someone switch a 5.5 or other gear set into my engine? The gears that came with the motor have 26 teeth, the ones I got to replace them have 21. The pinion gear that came with the motor have 15 teeth, I see them on ebay with 12.