45LC using standard factory ammo (so SAA-safe just about) out of a 16" carbine barrel will lay the thump on piggies and deer, etc. within 50-100 yards IF you can hit the vitals.
Looks like you can get a minor to near 50% boost in speed depending on load and barrel length -
http://www.ballisticsbytheinch.com/45colt.html
The big heavy loads may or may not be OK for your lever spoon - depends on which make, when made, etc. Just like on the revolvers. Even if it isn't a pressure issue with the big 300grn stuff the load could be too long to function through the feed system.