i7 should be fine, but again 3rd generation is still some while back when it was released (2012).
Considering they are already in their 8th or 9th generation, I'd still be looking something relatively newer.
I have a i5-6500 (6th gen) which is relatively cheap and pretty up to today standards.
I used to have a i5-3470 (i5 3rd gen) which was relatively okay in running Planet Coaster, but once I got the i5-6500 it was an entirely other world in words of performance.
As Planet Zoo is a continuation of that engine and looks/feels relatively the same, I'm sure I would have struggled with my i5-3470.
i7 3rd gen fits within the minimum specs, however, you still need the follow up numbers, as there are quite a bit of variations, for all we know, you might end up with least powerfull one of that spec range.
I'm sure it will run the game, but "i7 3rd gen" just doesn't give enough information of how well it will run the game.
Maybe someone else has experience with it.
In other words, I would advise against, but it would be nice if someonelse could contribute and give additional advice which could be useful to you.
These are always the things I tend to have a good look at what I'm buying, and if necessary just postpone it a little bit, untill I'm fully sure of what I want and if necessary have the additional funds for it if needed.