The design of my engine bay forced me to use a stock style mount. The offshore mounts require a vertical angle bracket, but because of the tunnels, I had to use a horizontal one. I knew that I didn't want a rubber mount because they were prone to moving around. The problem was solved when Eddie Marine came out with a billet mount. It's simular in design to the factory mount, but it's solid. It's also very nicely crafted and is quite attractive.
I used 4 1/2" bolts that passed through the stringer. Because of spacing I was forced to align all the bolts, however it would be better to stagger them. The connection would be much stronger. I believe the angle was a 3"x3"x1/2" 9" long. To help distribute the load and to dress things up, I also used the billet washers under the bolt head. I've seen some people use a piece of bar stock to help distribute the load onto the stringer. That setup would have better pull through resistance than mine. Between the nut and the angle, I used a stainless AN washer to prevent galling. The bolts were stainless button heads that were polished.