[ridin' again?]

The classic came pretty well set up. Only quick improvement for a little more agressive trail rider would be 64g weights instead of the 62's that came with it. But riding with a 340 you won't be going anywhere quick or fast. Fuel mileage will be great riding at 1/4 throttle while she is at 3/4+ the whole time.

 

[ridin' again?]

The lines on the pump should line up as the slack is taken up in the throttle cable. It will be behind a bit at idle if set correctly.

 

[ridin' again?]

awesome!! congrats on the success.
I'd go with the above oil pump setting, as it comes from someone who actually owns a sled a lot like yours (I don't and have been giving you general guidance rather than specifics). But if you want to be absolutely sure, the only way to set it is based on fuel/oil consumption.
Track: I usually give about 1/2" of sag in middle of the sliders with sled off the ground and adjust on the trail from there: loosen until it ratchets in deep snow at full throttle, then tighten until it stops ratcheting or only ratchets a bit under extreme abuse (you want it as loose as you can run it for power, speed fuel economy, slider wear...).

The info I gave him is right from the polaris factory service manual. I sure hope it's right.