Wow, that is kinda weird...I guess I would verify all of the jetting (main, pilot, needle jet and jet needle, econo jet) are stock since you have access to the manual....Can't think that there would have been any variations to the stock 2.5 slide cutaway...
If the slide cutaway is the only difference, you can probably bump up the pilot jet slightly from the stock 25 to maybe a 30. The larger cutaway allows a bit more air into the motor from idle up to about 25 percent throttle opening. If you have a slight lean bog at initial acceleration, that increase to the pilot jet would help cure that.
Still...doesn't explain why your sled has 3.0 slides???
I looked at the '78 Intruder manual also to compare. It had slightly richer jetting, but the cutaway was the same as the '79.....2.5. Dunno?