I tossed this out in another thread as was surprised not to get a response so I thought I'd try again.
I'm upgrading to a hydraulic roller for my 350 (Comp Cams XR276HR).
As far as camshaft end play is concerned: What are the most practical and especially reliable ways of establishing and controling endplay in a retrofit?
Are thrust bearings behind the cam gear a necessity?
I like the idea of the Cloyes Quick Button timing cover and the Hex Adjust timing set with the thrust bearing. I just don't know if I really need it.
Any experiences?  

How else are you go to control walk? A nylon button? The roller bearing button is the best solution.

Setting the cam walk with a dial indicator and the adjustable button wouldn't be a bad thing. You can take some of the guesswork out of it...  

Looks like I'll have a Cloyes Hex Adjust timing set with a thrust bearing and a Cloyes 3 Piece timing cover with a thrust button to work on the upgrade.
That should resolve any issues with the retro fit.  

I'm not sure if you understand this or not but I'll give it a shot...

Cam walk is not an issue specifically created by the retro-fit roller cam. Cam walk must be controlled with any roller cam as the lobes lack the taper and "fit" created on flat tappet lobes - and you could argue that high horsepower flat tappet applications even need a device to control cam walk.

Serious walk can be destructive to any roller cam and minor walk can affect total ignition timing at high speeds where vibrations are most severe and flex is most prevalent.  

Cam walk  is a simple concept.
My question regarded the options available to control the end play (cam walk). Seems that there are several.
I was curious to see if anyone had employed just a cam button in conjunction with a stock reinforced timing cover. I've heard that this will eventually fail under repeated use and either result in fluctuating ignition timing ( which you mentioned)or plain wear out.
The Cloyes pieces I've ordered not only allow for in the vehicle cam timing adjustment but also have the necessary thrust bearing behind the cam sprocket and thrust button which is accessible after the engine is assembled.
Should be a breeze.
My XR276HR, timing cover and gear set are there way. Thanks for the input.