Frank
Mattys gear recomendation is good and you can still utilize the stock 76 pitch chain with those gears. For a trail converted '05 440 pulling the stock 1.875" lug track that may be just a little bit too much gear. Another popular gear combo for the 440 is the 21/43-76. You will loose about 5 mph Top Speed from the 22/43 but you will have a little better low and mid range pull.
Take a look at this link. It is the Polaris Gearing Chart right out of the IQ Race Manual. It will help you decide which gear is best for you. You may have to click in the lower right corner of the charts to get them to expand for you depending on which Browser you are using. Keep in mind, it takes HP to go fast, and the stock 1.875" track eats HP.
Polaris Gearing Chart