Rem mod 581 is overbuild for 22LR has 6 rear locking lugs two piece bolt and double pinned barrel.
I machined new front part of bolt, added new one piece firing pin, machined the ejecting port a little longer, threaded front of receiver with 3/4" NC thread and installed 20" long "quite heavy" (.625" at muzzle) fluted barrel.
The magazine opening was spot tig welded with steel blank b/c installing much longer and wider clip would weaken the receiver IMHO.
I guess almost everything is possible even your old cooey as a 22K Hornet only if you can do it yourself in your spare time b/c
paying the gunsmith to do it would be cost prohibitive IMO.