Should I be worried about buying a shot out pistol? Or am I likely in good shape so long as it has rifling left?
Barrel Life of a 9mm Service Handgun is typically between 17,000 and 25,000 rounds of Standard Ammunition. Service Life of a typical 9mm Service Handgun is about 25,000 rounds. Even before getting to that end, periodic Armorer replacement of worn Springs should have occurred.
If you feel the Springs in the subject CZ75 are worn and require service, expect that 7,000 to 9,000 rounds have probably been fired thru it. Inspect the Barrel's Chamber and Rifling for wear using a Bore Light of some kind, noting any Wear in the rifling grooves and at the Chamber end/Rifling Beginning for any excessive wear. CZ Barrels in particular tend to be very long lived and tend to last the life of the Handgun, unless improperly cleaned.
You are probably worried about buying a Gun with a lot of problems, but I would not worry much about it, as most problems can be simply fixed with the replacement of some minor parts. But as I fix my own stuff, that's just me.