It is my opinion that for film photography it does not matter which camera body you buy. Naturally it has to be in good working order, but that's all there is about the body really. What does matter is the lens you mount on that body, and the film you put in the body.

For your learning experience I'd suggest using manual settings only. There is not many: shutter speed, aperture and focusing. Can't be too hard, but in reality that is already plenty enough to keep in mind when your background is in DSLR photography. And I think it would be a waste to invest into more advanced SLR body when any simple model can do what you need done.

Asking for a good camera body makes much more sense when buying a digital camera, for then you are effectively buying the film (sensor) and electronics too - not just a simple body. In a film camera all you get in the body is shutter release button and a dial to set shutter speed, plus an exposure meter of course. Aperture setting is done with a rotating ring on the lens and focusing is done with another ring on the lens. Now, of course there are those fancier film cameras that work aperture from a dial on the body and they have auto-focus and bells and whistles. You don't need those, you already have it all on your DSLR body. Keep it simple when your aim is in learning photography basics with film.