Reusable Code - Passing a IMyBlockType as a variable

I have an old code i have been reworking.
I had an idea to create a method which receives a list of blocks, the type is block you wish to cast them as, and a string variable as an action.

here's a full code of what i have, but IMO the entire thing isn't relevant.

Reusable Code - Passing a IMyBlockType as a variable