I'm surprised about the lack of enthusiasm regarding this rifle.
Honestly, I did't see anything to get enthusiastic about when I looked at them. Have you handled and worked the bolt on one? That said, there is nothing wrong with the rifle either. It is a good solid rifle that, with a little work and polishing, can make a great rifle that I wouldn't be ashamed to take to Africa. The biggest fault (for me) was the sling swivel stud on the furniture, and ho-hum finishing (not bad, but the bolts was a little rough, and furniture was bland). I handled several in both hogsback and American versions, and all had the same faults (as well as good features).
The price of the Ruger M-77 Mk. II is steep, but if you buy used you can save up to $1k on a rifle that has been scarcely shot (same with other makes/models). That is the beauty of buying a used "Elephant Rifle", people shoot them and then decide that they don't care for the recoil, it gets packed away in the back of the safe, then after a couple years sold in great condition. I think the CZ used to be the best buy for an inexpensive Express rifle, but that time has passed IMO. The CZ has went up in price and the new Winchester appears to a nicer rifle (at the same price)...but get what you like.
The one thing that you might want to reconsider is your choice of chambering (have you shot a .458 Mag.?), the .45s are great for Buff on up, but they are gross overkill for anything in NA. The recoil is significant, but not sharp, so with proper technique it can be managed (even fun, if you are a bit crazy like myself). The trajectory is the biggest fault, as shots on big Kodiak/Polar Bear (I assume that is what you would be using it for) or Am. Buffalo/Bison can be a decent distance (especially Polar Bear). This is why I would suggest a .375H&H or a .416Rigby (or their equivalent Ruger/Remington counterparts). I went through the same process as yourself, and being the sentimental fool that I am, decided that the .375H&H was the best combination of affordability (for reloading), power, and trajectory. The fact that it is 99yrs old and still well regarded for dangerous game didn't hurt my decision in the least. However I am getting ready to start a second project that will satisfy my desire for a really big .45cal boomer, so I understand the call of the .45+ caliber dangerous game rifle.