I'm not sure if newer Explorer or Sport Trac gauge clusters will swap. If they do, it would have to be out of a similar style. I do know that the first gen Explorer gauge clusters swapped with 1989-1992 Rangers and Bronco IIs, but I also know that the clusters were labeled as to what motor they were set to function correctly with.
Additionally, stock tachs tend to be somewhat inaccurate, typically they're just "good enough."
You can get white-face gauge things from different sources, IIRC Summit Racing sells some and a bunch of other places. What they sell is a sort of sticker type thing that gets installed on your existing gauges.
Aftermarket tachs are not all that difficult to install. In fact, installing one is what lead me to TRS years ago. Most aftermarket tachs require 4 wires: Ground, Keyed Power, Illumination, Tach Signal. Offhand I forget what color wires you need to tap into, but it's not hard. Provided I remember, I could look and see what I tapped in my Ranger to do it.