Just a few years ago, Marlin made limited production runs of lever-action carbines in .25-20 and .32-20 calibers.
Those would probably be my first choice for that .32 Mag conversion you have in mind.
The problem is, the Marlins in those calibers have become collector's items, and will be sorta pricey.
Second choice would be an M1894 .357 Magnum carbine, with the required breechblock, extractor work, and of course re-barreling to .32 H&R Magnum