This cam will easily allow an initial idle timing setting of 24 degrees - I wouldn't go lower than that. This affects the idle vacuum, and you need at least this much idle timing to pull vacuum upward. A steady vacuum gauge needle will confirm how much more initial timing you can use. My 406 Chevy has a similar XR282HR duration cam (9.5:1 compression) and likes as much as 28-30 degrees, but I keep it set to 24 degrees to prevent any part throttle ping (idle vacuum begins to drop below 22 degrees - automatic trans, 2500 stall). The lobe separation should have been higher (112-114 for better idle vacuum), but the Sportsman is unaffected by lower vacuum. This cam should also run well for your compression, regardless of the idle vacuum. I have my 406 Chevy running 7 degrees of vacuum timing @45%. This should also work for your engine. Of course, all these are ballpark numbers, but should be close enough to start out with. Just make small changes and keep an eye on the sparkplugs. Timing will affect the side electrode heat line - which should be centered in or close to the bend. With A/F, the ceramic should have an even light tan color deeper and at the outer portion half - with possibly a lighter .020 ring at the very end of the inner ceramic (firing tip) due to the MSD cleaning action.