I guess I have been lucky. I have never had a bad CZ. There have been some I didn't like so much, like the CZ75 Compact. I just never liked that pistol. I tried, but I failed.
The errant mill marks being what they are, I can relate, as I remember a Remington 40X I bought with those same mill marks under the rear receiver ring around the sear which put me off to Remington ever since.
I have had one apiece of the rimfire 452, the centerfire "mini" Mauser 527 and the standard sized 550. They have all been great rifles. My 527 was stolen, but I had at least 3000 rounds through that thing. I miss most the scope that was on it, as I was beginning to start to look around for a replacement barrel, or a replacement rifle.
I shot my 550 today. There is no doubt it is one of my finest rifles. Just a fantastic piece, accurate, and confidence inspiring.
I do not have a Model 70, but I do have a Model 54, its predecessor in production, and it is also a very high quality rifle, but I think it was made in 1926, so things were different then. 3 position "wing" safety, decent trigger, good sights, and shoots just fine if I do my part.
It seems to me that the weight of opinion here today is that you should get the Winchester. It also seems to me that you are leery of the CZ. If under these circumstances you buy the CZ, you will kick yourself for not listening to your reluctance if for some reason it disappoints. You will probably never really trust it, and it will have to work twice as hard to give you half the satisfaction you expect, while your desire for the Winchester is such that it could be half the rifle of the CZ, and give you all the satisfaction you seek.
Based on this, I'd suggest you get the Winchester. If it were me, it would be the CZ.