I think I'd splurge for the $5 or $10 version.
It's a somewhat daunting job the first time. Just take your time and read and reread the directions. It should be evident what to measure once you get in there. Just make sure you have the cam at the right position for the right valves.
There are several good threads here about it (one may have been moved to the FAQ).
Lastly, don't overtorque the valve cover bolts like I did.
That is a huge pain in the ass.