My 93 Ranger 3.0-liter has almost 290,000 miles on it, original engine and fuel pump. I've owned it since 1998, when it came to me with 122,000 miles on it. I've changed the fuel filter about every 60,000 miles.

The pump is not malfunctioning, however, I am contemplating replacing it soon, preventively. I won't do it myself, my shop estimates it will cost $500 ($800 with the Motorcraft pump and sensor unit).

I'd like advice and reactions to my plan.

 

My '94 4.0l has 350k and original engine and pump.

"Knock on wood", while you can replace it with a non-motorcraft pump, they don't tend to last past the 1 year warranty, and if they do then you are paying for another.
Find out what brand they will use.

Motorcraft pumps have 30 or 60 day warranty, lol, because if the last past 60 days they are good for 20+ years.

Failed fuel pump will leave you stranded, but so will a few other parts.
Hard call but I would leave it alone until or if it fails.