fastbike - if you are going with a single action revolver in 45 Colt, be aware that loads you develop for a rifle or carbine may be too hot for the revolver - that said, you may ind yourself developing different loadings (hotter for the rifle/carbine, milder for the revolver) and if they are confused with one another you may have problems. The single action revolvers (older 1873 style) still aren't really strong enough to handle steady diets of hotter loadings that you could use through your lever gun while hunting.
This said, the 357 may be a better choice and you may be able to settle on just one loading for both revolver and rifle. You can believe that the 357 has enough ooomph to handle whitetail from either firearm.
I believe both cartridges are a lot more versatile today than in years past. The 45 has a wide range of bullets and loading available but again, if you are using a cowboy revolver then milder loads are called for. The 357 is extremely versatile with a very wide range of bullets avialable. HTH. Mikey.