I'd be interested in a lever gun in this caliber. What does it offer that a .357 doesn't?
In a revolver, the answer is higher velocity and higher capacity (an additional one or two rounds, generally); or the ability to chamber a .357 Magnum-class cartridge in a firearm too small for .357 Mag (such as a Bearcat or Single-Six).
In a rifle, it gives you lower recoil with smaller, lighter projectiles. In theory, it should come with a more compact action, as well ... but I doubt that would be the case if a .327 rifle ever came to market.
I'm sure most of us that want a .327 rifle would also like to be able to run .32 H&R and even .32 S&W Long in it; but there's no guarantee that the capability would be there - especially for a bolt-action or an adaptation of an existing lever-action. So I don't really count cartridge 'reverse-compatibility' to be a benefit in a rifle.
Mostly, what .327 Federal would offer in a rifle, that .357 Mag can't, is the fact that it's .327 Federal.
@FrankenMauser and anyone else: I apologize if I'm hi-jacking the thread. Don't mean to. But I have a 4 inch SP101, chambered for .32 H&R and I've been toying with reaming it out to .327. Is that a good idea, or would I just be ruining a good .32 H&R?
I wouldn't do it.
To me, the 4" SP101 is primarily a target and small game revolver. In that regard, .32 H&R is plenty (for me).
While I do like .327 Federal, I shoot far more .32 H&R and .32 S&W Long in my revolvers. I like having the capability to achieve some serious muzzle velocities, but I usually opt for more sedate loads.
If you don't reload, it may be a better option to rechamber the revolver. But I reload, and most .32 revolver owners (who actually shoot them) do as well. So I often have reloading in mind when considering things like that.
My .327 Federal SP101 4", while currently my favorite of the group and the planned future sidearm for small game and big game hunting (when legal), has seen at least twice as much .32 H&R, and at least as much .32 S&W Long, as .327 Federal.