I took Dave's advice when I was building my 235 and it was pretty straightforward. One caveat, the instructions say to drill the block 3/4" deep and tap for the mounting bolts - two I believe.
Just so you understand, using a regulat tap in a blind hold 3/4" deep is not going to give you sufficient threads. Be sure your threads are deep enough so that at least 3/4" of the bolt is in threads either by using a bottoming tap or drill the holes deeper, but not much.
Don't panic if you drill through, the worse is a water passage so if you do drill through you can seal the hole simply by installing the adaptor.
Also, if you do happen to drill the holes at an angle, you can use a stud bent to accommodate the off-angle.
