One of the posters on another forum has had really fine results with his .451/465 grain flat nose bullets in a 1:20 twist .45 caliber Knight in-line. I've shot the same bullet from a 1:30 twist Renegade and got good results. But did not match the 1:20 twist results.
My vote would be for finding a Lyman Great Plains with a bad bore and having it relined to .451/1:20 twist. In fact, that is on my to-do list for 2015. The Great Plains has a classic look and fits me nicely at the shoulder (I have a .54 and a .50 Great Plains - both flintlocks).
