I'll make it simple....forget the mount and just clamp the outboard directly to the transom.
I did that on mine and it worked fine....well, except for the crazy angle of the DS transom. But that isn't really a big problem, depending on what you have for an outboard. I did end up bolting a plywood mounting board to the transom to angle the outboard properly, used 3 bolts and it is fine.
When I bought my DS II it had a motor mount (fixed height) installed by the original owner (and rebuilt by the 2nd owner). I removed it before using the boat since I prefered clamping the motor to the transom and also wanted it on the port side instead of the starboard location of the mount. That bracket was attached with 3 bolts and one lag-screw (the lag screw was used in place of a bolt that would have been hidden by the cockpit seat.
If you do add a motor mount, be sure to use a good marine sealant on all fasteners, the DS II transom has a plywood core and if not sealed water can get in a rot the plywood.
I'll attach a picture or 2 of my boat. The picture that shows a motor clamped to the boat is before I added the motorboard, it is a short-shaft and worked OK. I have more pics showing the bolts for my motorboard, but I'll have to reduce them first and I need to leave for work right now.