If you can find a cheap .410 single-barrel shotgun you can have a .32 rifle barrel made from scratch for it and get away LOTS cheaper than buying one of the new Marlin Leverguns.
I had a pre-war H&R .410 single-shot which was built on the old tiny receiver, much nicer than the clunkers they sell now, and which I wasn't using much. John Taylor at Taylor Machine produced a 26" long rifle barrel which interchanges with the .410 barrel, so that I still have use of the shotgun. Cost was around $300, plus sights. The gun weighs only 5-1/4 pounds and balances like a dream.
It's also VERY quiet with .32 S&W Long factory loads, like shooting standard velocity .22 LR in a typical sporter. I went with the .32 S&W Long because these little revolvers have always been my favorite trail guns and in a strong gun there is little or no advantage to the .32 H&R Magnum. The factory loads are "ordinary" but I get 2-inch groups at 50 yards with iron sights. They are much more effective on small game and wild turkey than any .22 rimfire, but destroy less edible meat than a .22 Long Rifle HP or .22 WMR.
My favorite .32 Long Rifle loads use the Saeco #322, 120-gr. LFN .32-20 Winchester bullet, as-cast, of wheel weights, unsized, tumble lubed with Lee Liquid Alox. The minimum load which safely exits the 26 rifle barrel every time is 1.2 grains of Bullseye. This "silent but deadly" 450 f.p.s. BLOOP load, is seated out and crimped in the lube groove, so that the bullet engraves on the front end when the action is closed. Its essentially a CB cap on steroids.
The same bullet loaded with 1.8 grs. of Bullseye provides 850 f.p.s. in the rifle and 720 f.p.s. in my 4 S&W Model 31. This is a full power revolver load at SAAMI pressures, but with its heavier FN bullet is much more effective than the usual 98-gr. LRN factory stuff. It still has a mild report, measured at 85-86dB, which compares to the pop of a Ruger 10/.22 with high speed .22 LR.
A heavy load which approximates the .32 H&R Magnum or .32-20 for use in modern post-war solid frame revolvers such as the post-war S&W Model 31, Ruger SP101 or Single Six or any other revolvers chambered for the .32 H&R Mag. Uses the Saeco #322 bullet with Federal 200 small rifle primers from 5.5 to 6.0 grains of Alliant #2400. This significantly exceeds SAAMI pressures for the .32 S&W Long, but is safe in the Ruger revolvers and post-war .32 solid frames. It gives about 900 f.p.s. from a 4" revolver and 1200 f.p.s. in my .32 S&W Long rifle.
If you decide to build one of these American Rook Rifles the chamber body dimensions should be minimum SAAMI, but you want a rifle-style throat with .314" diameter forcing cone entrance and 3 degree included angle origin of rifling. Rifling specs should be nominally the same as for the .32-20, .300 bore x .310 groove, with 16" twist, but if you have a slow twist .30 cal. rifle barrel, of 14" per turn or even a 20 twist .30 M1 carbine blank, this will also work fine.
