I'd second the idea of a second tranny for the wheel drive. Start out with
a reduction of about 4:1 (rear end ratio) and then you can gain another
about 3:1 or more reduction by the gear selection. Having the gears in a
second tranny will also allow you to have 4 choices for speeds which will
make the depth of the cut for the snowblower adjustable for the various
depths of snow.
You're probably going to be wanting to do about 3mph when the engine is
turning for 60mph on the first tranny so that ends up with a reduction of
about 20:1 and that means that you need to have about 5:1 for the
intermediate reduction to the second tranny clutch something easily possible
with a chain drive.
Please also note that chains are transmitting tension, not torque so a
larger gears will allow for more power transmission for any particular chain
size. You're also not going to be transmittng that much power (maybe 5hp)
so the requirements are not going to be that hard for the chain drive.

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Why isn't there an Ozone Hole at the NORTH Pole?