What is acceptable rocker arm wear?

I will be rebuilding my renix 4.0L in the upcoming weeks. It is already completely disassembled and ready for maching work. I have been going over my parts and making a list of parts that definatly need replacing and which ones I can use again. I would build a complete stroker, but my budget is fairly limited, and I still have to get this non-running XJ road worthy.

My question falls on the rocker arms. What is acceptable wear on the tips? I know some need replacing, since the valves didn't rotate and destroyed the tips of the rocker and the valve. If I replace those, should I replace all of them?

If you are going to the time and expense of rebuilding the motor why not replace all the rockers, pushrods etc. Less to have to worry about going bad.

After looking at the primary head I am rebuilding, and just now taking apart my spare head, that was looking like my only option. It is looking like I am going to have to replace the entire valvetrain anyway. I was just trying to make my budget go as far as possible.

I really appreciate the input.