You know, the Mod.70 is really a more complicated copy of the origional opposing lug, cock on opening rifle of fame, the Model 98 Mauser, so is the CZ in many ways. I like the CZ very much tho it does have it's flaws. The CZ set trigger is great when adjusted but out of the box it is rather harsh to say the least. The Mod 70 has a following as do many Winchesters just like the 94 which is far inferior to the Marlin design. The 70 has a three piece mag assembly, not very rigid, cost effective but poor in design. The recoil lug is also too small for the harder kicking calibers which is why so many of the big caliber Mod. 70s have cracked stocks. The trigger is good, simple and stone reliable, however the safety is small and not that great for getting it off in a hurry when something wants to eat or stomp you. On the other hand he safety is very safe as it cams the cocking piece away from the sear instead of just blocking the trigger as the safety of the 700 Remington does. Do not get me wrong, I am not saying the Mod 70 is junk, it is not, but it is no where near perfection either, but what action does not have room for improvement?
I think the Mod 70 is vastly over ratted by some of it's fans but the Mauser is also.
The Mod. 70 was introduced in 1936 and lots of developments have come along since then. Many of these developments can be incorporated through after market companies into the 70, (or other guns like the Mauser). The biggest down side of the Mod 70 is rather poor gas control if one ever has a case head seperation. A hole on the left side of the action would help here but even then the gas control would not come close to the Mauser though the CZ does.
In reality choose what you like, neither are bad I think that in some ways the CZ blows away the Winchester but the CZ is not a classic. Would I build one of my customers a custom rifle on a Mod. 70? Damn right I would but so would I using a CZ action. I lean towards the CZ, but that is more personal then based on draw backs of one over the other. I also like building the "big" rifles and the 70 does not have the barrel shank diameter for this. One more point, before stripping a Mod. 70 to build a rifle look at the potential collector value of the rifle.
For example tearing apart a rifle worth $1500 when you could get a CZ 550 for $550 does not make much sence. If this is the case sell the 70 to one who loves them and have money for building your rifle, or find one which has little or no collector value.