http://www.northerntool.com/shop/tools/product_200442160_200442160
Here's mine after I got it hooked up last fall. Northern Tool says its 30,000 btu. Works well in SW Michigan. I have a ceiling fan, and a fan mounted on the wall to move the heat around. (about a 23 x 23 attached garage.)
Just...
If the block is painted (glossy), you may have a shot at it. Vinyl does not stick to porus surfaces. Most likely it will not stay on the concrete block. You could try high tac vinyl.
Your best bet would be to get a sign made and then attach the sign to the wall
I picked up an XL cabinet and got a free wall cabinet yesterday. Luckily enough, the day before I got a $25 off cupon when you spend more then $200. My receipt showed I saved something like $155.