That is correct, I used a vise to add the extra bend in the L-brackets. What I use for making special brackets and such is a vise brake like this one:
http://www.grizzly.com/products/item.cfm?ItemNumber=H3243. It's one of those types of tools that you pick up on a whim, then wonder how you got along without it. I use the vise brake so much, I bought another vise for my workbench so I could keep them installed all the time.
Anyway, another method for installing a monitor with a shelf-style frame is to attach it to the side panel of the cab, like how the Midway cocktails were made. The side opposite the coin door swung down (the top is permanently attached to the side panel), and so the entire top, side, and monitor swings out of the cab when you open it up. Below is a pic of how I installed a W-G K7000 in my cocktail. Notice how I built a riser base for the monitor to center the monitor in the top cutout.

This makes it very easy to access the entire monitor and guts of the cocktail. There are more pics at
www.oscarcontrols.com/cocktail.