Any recommendations on how much up the caliber to shoot safely?
Example:
I slugged the bore of my 357 magnum snub nose and it is bored exactly to .356

Can I shoot the lead cast bullet from my Lee mold without resizing them?
They come out of the mold sized .358 or should I use a sizer and size them to .357 exactly?

Thank guys

That would work in a rifle. Not in a revolver necessarily. You need to measure the throat of each chamber and size to fit that dimension if you're looking for best accuracy. If your bullets are smaller than your throats you'll get gas cutting and sloppy entry into the barrel. On the other hand, if your bullets are soft enough, they may bump up upon firing to effect a good seal. One way to find out. Try what you have and see if they work. If satisfied, you're good to go. If not, you need to look at throat diameters, chamber alignment, forcing cone roughness/trueness, alloy hardness (too hard/too soft), bullet lube efficiency, yada, yada, yada.

All I can add to gnoahhh's post is that conventional wisdom says, all else being the same, as cast will be more accurate than sized.

If you're worried that you might blow yourself up by forcing too large a bullet down your barrel, don't. It'll swage itself down. Cast lead bullets are meant to do just that. Well, within reason.