For the conversion it doesn't matter which FOV type you select.
I assume you meant 360 distance with 1.5X is shorter than hipfire, not greater? And this is correct with your settings as hipfire is matched using 360 distance, while the ADS/scope is using viewspeed (i.e. FOV based match). And since the 1.5X FOV with your settings is actually higher than the hipfire FOV for Source (112.3 vs 106.26) you're getting a shorter 360 distance.