500 fpe at the muzzle on a 100 grain sabot moving at 1500 FPS is more than enough. I would stick with shots with in 75 yds and shot placement is critical because of the lack of bullet fragmentation. Have it re chambered to 3" and you can get 750 fpe at the muzzle.
I have a bolt action 410 and had rifle sights put on it several years ago. I have shot several deer with it and a couple hogs. About 75 yards is the max for acuracy but it is the king of knock down power out to there
Haven't looked at 410 slugs lately, but the ones I have shot in the past I would consider marginal at best for deer and only at short range like bow range. Being that it is short range I would just use 45LC, bigger bullet with momentum gets the job done at close range for sure. The thin walls of a Judge I would not use heavy loads in the 45LC either.