I'd vote for tach, shift light and the oil gage. If the car is pretty stable
and handling well then you have time to check the tach. It can tell you a lot
about how the car is running, especially on the long course. Why go the full
5 miles if you're not running right? Also in my experience backing off the
throttle with the Hilborns running a little rich actually got the rpm's up.
Net result, a little better speed in the 5th mile. I wouldn't have sensed that
without a good view of the tach. If your ride is too wild for a glance at the
tach either you're running on the stretch side of 200 (and sure don't need any
advise from me) or you've got a handling problem that needs attention.
If you have enough battery then by all means put good lighting on the gages.
The Bonneville sun is rough on old eyes. We use flashlights on occasion when
working on the car under a tarp.