Tappets are easy, best thing you could do is buy a haynes manual, as would have everything in there you need.
There is a tool you can get called click adjust, to adjust these and other ohv finger lever tappets that take out the guess work, as these suffer badly from rocker shaft wear, the trick is to pull up the end of the rocker you are adjusting to take the slack(wear) out.
Makes a big difference, as does a alloy rocker cover, a lot quieter with these.
tabetha