PHSC_Jono,
I own several CZ Model 550 rifles, calibers 6.5x55 through 500 Jeffery.
The rather expensive .500 Jeffery would neither feed Kynoch live factory ammunition from the magazine, nor would it chamber same if you massage one from the stubborn magazine, unless you really leaned on the bolt handle with enough force that it made me nervous.
So, not trusting the goobers who sent it out the door without function testing it first, I paid through the bloody nose to have a local Gunsmith repair it.
Now it feeds like a hog and I am happy with it.
All of my other CZs (the way less expensive versions) have worked very well with no function issues.
The Model 70 Winchester is a fine rifle, if you stay away from the push-feed ones made in those dark years of the mid-1960's through whenever they returned to the original / full length extractor type action of today.
When I worked in a gun shop, I saw a couple of them that would not feed with these new, short magnums because of the rather square shoulders on the cartridges.
It seems to me that either rifle will serve you well, even if either rifle required some hand filing to make it work correctly.
I slightly prefer the CZ, at least for larger calibers, mostly because the action is proper size for said larger cartridges, also CZ's tend to be better than very accurate and I like the deeper / larger capacity magazine.
Regards,
Velo Dog.