405 Lion Medicine

Finally found shotgun for 405 conversion. Its "FELAG ARMS" Belgium 16 gauge Nitro proofed, Greener crossbolt with 4th bite, Gusseted. Locking lugs timed "On circle" barrels marked in Gold inlay "SUPER QUALITY" tight on face, open or closed. False side locks. Test fired it with RUGER load 45-70 barrel insert, both sides. No problem. Large fire-pins will be redone, bushed, as Ellis Brown suggested. Who makes good barrels for this type conversion for 405 Win. ? Is rifle twist same as in RUGER 405 and 450-400 ?