Do I need to install anything else when I install aftermarket long duration/ high lift cams?

I am going to install APEXi SAFC II.

Also, I would like to install valve springs but unfortunately I know of no aftermarket valve springs available.

Should I install the Fidanza cam gear or will it not make any difference since the intake cam and exhaust cam are linked or whatever.

Thanks for your input. By the way, I'm looking to install 268 duration cams...intake and exhaust.

And what are shims?