It'll handle a deer and even larger if you desire and work up the loads. I haveharvested whitetails, mule deer, black bear and moose with my 50 cal ML's. The range is not upto a CF, being 100 to 150is whatmost feel confident with, however those who possess the skill and will to put forth the effort can extend the range a little.
My knight disc likes to shoot Pyrodex RS or P powder(I use loose powder and never tried the pellets in it so can't comment in that regard) - 80-100gr volume. My bulletschoices were:250gr Barnes MZ Expanders, 250gr Hornady XTP's and Nolser 300gr parts - all use the black MMP short sabot. I still own the knight and shoot it though I have added others over the yearsthat seethe hunting action. It's too good of rifle to let go for what it'll fetch so it remains in my cabinet and probably always will have a slot!
As far as 3" eye relief, it's not a tone but may be fine. My knight has a B&L elite 3000 on it that affords 3" at the highermag. and never caused me any grief. That said I know others who have problems withmore then 3" eye relief so a lot depends on the shooter.
FYI you may want to scroll down the main page and check out the Blackpowder forum.
Enjoy and good luck