Vanilla Minecraft Pick Block is an only creative thing. ForgeHooks makes it select the item if it is in your hotbar, no matter what gamemode you are in.

Suggestion:

When the pickblock key is fired, if you are in survival mode and you have the block in your inventory(not hotbar), it should swap the items. I was messing around with this on my own, i was having problems with ghost blocks...

It is definitely doable, I would recommend looking at ForgeHooks's pickblock method as it is more detailed. I was having troubles doing it my self, even though i was doing basically the same thing as autorefill. I kept getting issue of moving invalid itemstack or i was getting ghost blocks that didn't actually exist. For you, seeing as you know the code fairly well now, it'll probably be fairly easy to implement and you'd do it "properly", I threw together scrap code just to see if I could do it myself.

Most likely doable, but certainly something to leave an option for (probably default off). Will need to research the behavior of it in creative mode first, but moving things would be similar to autorefill.