I have a Howell TBI running my 258.
I was looking at how to view all my engine parameters.
Found this.
http://www.dynamicefi.com/EBL_Flash.php

Here is the heads up display
http://www.dynamicefi.com/EBL_ScreenShots.php

A complete dashboard display of EVERYTHING.
plus you can customize the PROM without removing the ECM or chip.
Looks pretty cool. Would be easy to make into a custom dashboard.
Probably wouldn't hold up as well as gauges under rough offroad abuse,
but this might be worth playing with.
Whole thing is cheaper than a digital combo gauge.
$350 with a do it yourself installation of the board into the ECM.
J.B.