Jim,
Shortening it will reduce the weight, but not proportionally. The center area has some heavy frame and impeller components - and the gearbox.
The body of the blower would be fairly easy to shorten.
Unless you routinely blow deep snowbanks away or most snowfalls are over 18" you could cut another 100+ pounds by taking out the upper auger - it's driven by a roller chain that could be shortened to drive only the lower one. Shortening the lower auger might be easiest by cutting a chunk out of the middle and coupling it with a pipe sleeve under the paddles. It would be best if the machine is a little wider than your rear wheels. No problem fitting to Cat I - may just need smaller pins. If your tractor has a FEL the balance would be ok. If not, may need weight on the front.
These big machines sometimes go very cheap at auction - good luck !