In one of my old (Circa 1970) nationally-known and respected reloading books, they used a Winchester Model 94 in .32/40 caliber for testing. The bore measurement was .3205".
The Cartridge specifications were:
Bullet Diameter Jacketed and Cast = .320" and .321"
Maximum Case length = 2.130"
Trim-to-Length = 2.120"
Maximum Overall Length (with Bullet) = 2.500"
In my opinion, you should NOT
use jacketed bullets of any greater diameter than .320" in the rifle with a slugged .320" bore or .319" in the rifle with its bore measuring .319".
Obviously, if the bullet is oversized, shooting it will increase the chamber pressure due to the bullet being a tad too big for the bore unless you can shave down or swag down the bullet to no large in diameter than the bore-size you're planning to shoot it in.
I dunno how much it would raise the chamber pressure, but it will surely
raise it. Since I'm SURE you don't wish to create a dangerous situation or possibly blow up a good rifle, I'd stay away from maximum loads with bullets that are larger than the diameter of the rifle in which they're shot.
Have you considered #2 alloy lead bullets with a copper cup on the back of the bullet to reduce leading?
Perhaps a better question is, "Are copper cups available for that sized bullet diameter (.323")?"
If you're gonna error, I'd error on the side of SAFETY.
BETTER SAFE THAN SORRY, my friend...
Strength & Honor...