What’s “proper”?
Good question. Hopefully the answer is not resorting to the tech-saves-everything solutions usually found on TNG.
The question is, why do it? To save Spock? He's was in there trying to save the ship by restoring power in a highly irradiated chamber. It was too intense for any human to tolerate. Spock's Vulcan stamina or whatever made him the only logical choice. Beaming him out would have only condemned the ENTIRE CREW to death.
Spock made his choice.
Agreed. Further, one of the key messages of the film--about facing death and sacrifice--would have been completely lost if Spock was somehow saved. One a few times a sci-fi movie character died for a justified reason.