86' 300E lifter noise

[can-do]

Greetings All,

I'm trying to clear up all the searches I've done on this problem. The engine has 195,000 and since I've owned it this engine has ticked slightly on cold start up but clears up after oil pressure comes up. Recently the ticking sound has gone to a clatter sound.
I've read all the posts on either lifter change out or camshaft lobe problems on the older model engines. Can someone clear up a few questions about all of this?
First, how can you check the lifter to ensure that this is actually the culprit? Second, can the DIY change out the lifters without any special tools? Third, does a different size shim have to be installed to account for wear or is the original o.k. to use if the lifter is changed? Fourth, if the cam lobes are indeed worn, how does one measure the wear without removing it, or will that become obvious upon visual inspection.

Any and all info will be well appreciated,

Charles