A quick look through Lyman #49 shows that all the visually straight rifle cartridges in current production actually have some taper.
If you want a truly straight case you will be shooting a revolver round in a rifle.

Marlin does not make a .357 Maximum lever action because it is too long for the 94 and they would not sell enough to bother modifying the 336 for it.

What's the objective here?