What if the boss pushes to override safety procedures?

First to need to have a record of your recommendation to him, then you assess the change in procedure and try to mitigate the risks.  You may find that there are more experienced staff, including the boss, who can assist with this.

Safety Management and safety procedures are in place for a specific purpose, and that is to ensure safety. If you allow or agree to breaching procedure or protocol because the BOSS said so, you might as well pack your bags. Should anything unfortunate happen, the BOSS will be the last person to face the consequences.

This is quite a common scenario actually, and I am sure you are not the first one.  

You can try finding facts about fines and loss of business/profit due to these type of breaches if the human factor isn't important enough to your boss. Some people need a little more persuasion than others, perhaps there is something in the middle that can be less hazardous and less costly, at least for the time being. 

Make sure you have followed what is reasonably possible and consulted your boss, staff accordingly. In the end it is up to your boss to allocate resources/finances, hence the absolute responsibility lies with your boss too. I understand you cannot go above what is in your powers, but you don't have to condone it either. Just make sure your view is official. 

Safety procedures should not be breached at all cost as human life might be lost.

That depends on the Organisational Policy.

Stand down a while, Verify his reason to the subject matter expert. May be he is right as he experienced with the situation. But may be he is wrong and his assesment is not correct. And maybe the procedures it self is not updated or not suit with the work condition.