Change UNABLE TO ADD ITEM Message for all product on 7.1 - and adjust Add to Cart message for all out of stock

Site URL: https://www.anderlegallery.com/

I found a couple of solutions for slightly different requirements posted by @creedon in another thread - however, I couldn't adapt the script to what I want. 

I need the change in title and message on the "Unable to Add Item" popup to apply to all product detail pages. Since it will only pop up when the item is out of stock, it can be a global change. 

In addition to that - the Add to Cart message would ideally change if the item is out of stock  - to Please Call. 

These are all one-off items, antiques - and many too large to use stock shipping options, so all of the items that are too big to purchase online have been set with zero stock. (When products are sold, I will set to hidden for the store owner, so there will be no conflict with genuine out of stock.)

Here is a specific product detail page - https://www.anderlegallery.com/shop/p/chinese-bronze-seated-buddha

Site is not live so password is

WGKAcW34ke

Thank you very much!

Although this might be helpful to know under other circumstance, I've simply hidden the add to cart when product is out of stock - this  works perfectly well. So never mind my question. 🙂

Thanks