Curt: you may wish to contact The Montana Rifleman about rebarrelling your Marlin. I used them to rebarrel my Winchester Big Bore in 444 to a 26" bbl with full length mag tube and it is both beautiful and deadnuts on accurate, grouping under 1" at 100m with any load I can throw down that tube.
The Montana Rifleman makes their own barrels, hand laps them before installation and makes certain your headspace and functioning is proper. I may well go back to them for another barrel for something, someday.