That 1 1/8 tapered to 1 inch barrel will be pretty heavy....I built a .54 back in the 80s before swamped barrels became popular and it's 1 1/16 ro 15/16s...Mine is 38 inches long and it's not too bad but I've often wished I had stuck to my guns on a swamped barrel...

I know you'd prefer a Hawken style but you can get a .54 from Jim Chambers in his Isaac Haines gun...That would make a nice, light weight hunting rifle...