The current NHRA correction factor for supercharged/turbocharged at Bandimere is :
Convert ET to sea level x .9702
Convert MPH to sea level x 1.0281
Convert sea level ET to Bandi x 1.0307
Convert sea level MPH to Bandi x .9726
All caveats about the applicability of correction factors apply, these will give you a "best estimate" of a corrected time under identical strip conditions, and same environmental conditions at the other altitude.