The other alternative is buy a used SB2 Handi or just a frame in the classifieds here and send it in for an accessory barrel and stock set, then you'd be assured of getting a late model barrel, you can also get a upgraded stock if you choose to, I only send in frames with no stocks, shipping is about $10 insured USPS priority.
I haven't shot cast in my .44mag yet, but I have shot 355gr cast in my .444 Handi which is also a Marlin made barrel, but is 1:20".
Another place to check is
http://www.whittakerguns.com/ they have great prices and are excellent to deal with.
Tim