Stephen, not much more to add than is in this thread. The Soozi 140 is fine, but the boat will take a lot more speed than the engine delivers.
The DF150 is a big lump of motor, (215 kg vs around 195 for the DF 140 or optimax 150 or etec) and I wonder if it would be on the heavy side on the back of a 5.8.
Would the 6.2 and DF150 be the better 4 stroke option?
On other things:
-get a through hull depth transducer fitted under the deck, or a well made so you can fit one later.
-make sure you get a stainless frame made for the windshield that you can hang onto as you move forward past the console
-have it delivered with a cover