I'm concerned with the bearing material, but also you should really invest in a mechanical oil guage. The stock gauge is operated by a sender that only registers @ 7 psi. There is a a write-up on making the stock gauge work correctly and if you want, you can give that a try as well. This was just discussed several weeks ago with another member, but can't remember who all contributed to it. Just use the search function here on FTE in the 87-96 section. The install and cost of time, will be worth it, say if in fact you lose complete oil pressure, say from a Fram filter(Orange Can of Death) that collaspes inside for instance.

I also own a 4.9, and always noticed a copper in the oil when I would drain it. I had to install a new oil pan gasket last year and I removed the lower main caps and noticed that some of them were starting to show copper. I always had that notorious dry, start-up rattle( I hated that every time I started it) From what I have read, the 4.9' were notorious for going without oil and water, and still wouldn't blow up. There one of the most infamous motors built. Long story short...

I installed a oil-prelubing system in mine, so I could prime the remote oil filter and the galleries before starting. No more rattle on start-up and after draining the oil, 1st time in 3 months when I installed, I let the dain pan sit for a day and I couldn't see any copper showing. I hope to eventually pull the motor and/or completely overhaul it. even at best, I could roll in new main bearings, and that would easily get my by for another 50K miles.

Hope this helps.