I have a 1992 LT1 with 1994 heads with the coded digital gauges.
When I turn on the ignition {not starting yet} the oil pressure gauge reads
99lbs.When I start the engine it goes to 70-80lbs. When it warms up to
operating temperture it climbs up to 99lbs again. Seems like oil pressure should drop a little when warmed up. If the oil pressure gauge is okay what else
could be the problem? Thank You

Something is wrong with your gauge or sender. 99lbs is super high and impossible with the engine not running.